chemistry 1.2
TRANSCRIPT
ChemistryChapter 1 - Section 2
How Elements
Bond
Monday, July 9, 2012
Bonding
Monday, July 9, 2012
Bonding
✦Atoms form bonds with other atoms using the electrons in their outer energy levels.
Monday, July 9, 2012
Bonding
✦Atoms form bonds with other atoms using the electrons in their outer energy levels.
✦Atoms have four ways to do form bonds.
Monday, July 9, 2012
Bonding
✦Atoms form bonds with other atoms using the electrons in their outer energy levels.
✦Atoms have four ways to do form bonds. 1.by losing electrons
Monday, July 9, 2012
Bonding
✦Atoms form bonds with other atoms using the electrons in their outer energy levels.
✦Atoms have four ways to do form bonds. 1.by losing electrons2.by gaining electrons
Monday, July 9, 2012
Bonding
✦Atoms form bonds with other atoms using the electrons in their outer energy levels.
✦Atoms have four ways to do form bonds. 1.by losing electrons2.by gaining electrons3.by pooling electrons
Monday, July 9, 2012
Bonding
✦Atoms form bonds with other atoms using the electrons in their outer energy levels.
✦Atoms have four ways to do form bonds. 1.by losing electrons2.by gaining electrons3.by pooling electrons4.by sharing electrons with another element
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Bonding
✦Atoms form bonds with other atoms using the electrons in their outer energy levels.
✦Atoms have four ways to do form bonds. 1.by losing electrons2.by gaining electrons3.by pooling electrons4.by sharing electrons with another element
✦We will be studying each of these in Section 2.
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1 & 2. Gaining and Losing
Electrons
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Sodium and Chlorine
Monday, July 9, 2012
Sodium and Chlorine
Sodium is a soft, silvery metal.
Monday, July 9, 2012
Sodium and Chlorine
Sodium is a soft, silvery metal.
It can react violently when added to water or to chlorine.What makes sodium so reactive?
Monday, July 9, 2012
Sodium and Chlorine
Sodium is a soft, silvery metal.
It can react violently when added to water or to chlorine.What makes sodium so reactive?
Sodium has only one electron in its outer level. Removing this electron empties this level and leaves the completed level below. Sodium is then stable.
Monday, July 9, 2012
Sodium and Chlorine
Sodium is a soft, silvery metal.
It can react violently when added to water or to chlorine.What makes sodium so reactive?
Sodium has only one electron in its outer level. Removing this electron empties this level and leaves the completed level below. Sodium is then stable.
Chlorine forms bonds in a way that is the opposite
of sodium—it gains one electron. When chlorine accepts an electron, its electron configuration becomes stable.
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Monday, July 9, 2012
Forming Ions
Monday, July 9, 2012
Forming Ions
As sodium atoms lose an electron they become more stable.
Monday, July 9, 2012
Forming Ions
As sodium atoms lose an electron they become more stable.
But by losing an electron, the balance of electric charges changes.
Monday, July 9, 2012
Forming Ions
As sodium atoms lose an electron they become more stable.
But by losing an electron, the balance of electric charges changes.
Monday, July 9, 2012
Forming Ions
As sodium atoms lose an electron they become more stable.
But by losing an electron, the balance of electric charges changes.
=
Monday, July 9, 2012
Forming Ions
As sodium atoms lose an electron they become more stable.
But by losing an electron, the balance of electric charges changes.
11 protons11 electrons(neutral)
=
Monday, July 9, 2012
Forming Ions
As sodium atoms lose an electron they become more stable.
But by losing an electron, the balance of electric charges changes.
11 protons11 electrons(neutral)
= but
Monday, July 9, 2012
Forming Ions
As sodium atoms lose an electron they become more stable.
But by losing an electron, the balance of electric charges changes.
11 protons11 electrons(neutral)
after losing one electron= but
Monday, July 9, 2012
Forming Ions
As sodium atoms lose an electron they become more stable.
But by losing an electron, the balance of electric charges changes.
11 protons11 electrons(neutral)
after losing one electron= but 11 protons
10 electrons(positively charged)
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Forming Ions
As sodium atoms lose an electron they become more stable.
But by losing an electron, the balance of electric charges changes.
Sodium becomes a positively charged ion because there is now one fewer electron than there are protons in the nucleus.
11 protons11 electrons(neutral)
after losing one electron= but 11 protons
10 electrons(positively charged)
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Monday, July 9, 2012
Forming Ions
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Forming Ions
In contrast, chlorine becomes an ion by gaining an electron.
Monday, July 9, 2012
Forming Ions
In contrast, chlorine becomes an ion by gaining an electron.
Monday, July 9, 2012
Forming Ions
In contrast, chlorine becomes an ion by gaining an electron.
=
Monday, July 9, 2012
Forming Ions
In contrast, chlorine becomes an ion by gaining an electron.
17 protons17 electrons(neutral)
=
Monday, July 9, 2012
Forming Ions
In contrast, chlorine becomes an ion by gaining an electron.
17 protons17 electrons(neutral)
= but
Monday, July 9, 2012
Forming Ions
In contrast, chlorine becomes an ion by gaining an electron.
17 protons17 electrons(neutral)
after gaining one electron= but
Monday, July 9, 2012
Forming Ions
In contrast, chlorine becomes an ion by gaining an electron.
17 protons17 electrons(neutral)
after gaining one electron= but 17 protons
18 electrons(negatively charged)
Monday, July 9, 2012
Forming Ions
In contrast, chlorine becomes an ion by gaining an electron.
17 protons17 electrons(neutral)
after gaining one electron= but 17 protons
18 electrons(negatively charged)
It becomes negatively charged because there is one more electron than there are protons in the nucleus.
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Monday, July 9, 2012
Forming Ions
Monday, July 9, 2012
Forming Ions
An atom that is no longer neutral because it has
lost or gained an electron is called an ion.
Monday, July 9, 2012
Forming Ions
An atom that is no longer neutral because it has
lost or gained an electron is called an ion.
Sodium ion is represented by the symbol Na+
Monday, July 9, 2012
Forming Ions
An atom that is no longer neutral because it has
lost or gained an electron is called an ion.
Sodium ion is represented by the symbol Na+
A chloride ion is represented by the symbol Cl-
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Bond Formation
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Bond Formation
The positive sodium ion and the negative chloride ion are strongly attracted to each other.
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Bond Formation
The positive sodium ion and the negative chloride ion are strongly attracted to each other.
This attraction, which holds the ions close together, is a type of chemical bond called an ionic bond.
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Bond Formation
The positive sodium ion and the negative chloride ion are strongly attracted to each other.
This attraction, which holds the ions close together, is a type of chemical bond called an ionic bond.
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Bond Formation
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Bond Formation
Sodium and chloride ions form an ionic bond.
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Bond Formation
Sodium and chloride ions form an ionic bond.
The compound sodium chloride, or table salt, is formed. A compound is a pure substance containing two or more elements that are chemically bonded.
Monday, July 9, 2012
Bond Formation
Sodium and chloride ions form an ionic bond.
The compound sodium chloride, or table salt, is formed. A compound is a pure substance containing two or more elements that are chemically bonded.
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More Gains and Loses
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More Gains and Loses
Can elements lose or gain more than one electron?
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More Gains and Loses
Can elements lose or gain more than one electron? Yes!!
Monday, July 9, 2012
More Gains and Loses
Can elements lose or gain more than one electron? Yes!!
Magnesium, Mg, in Group 2 has two electrons in its outer energy level. Magnesium can lose these two electrons and
achieve a completed energy level.
Monday, July 9, 2012
More Gains and Loses
Can elements lose or gain more than one electron? Yes!!
Magnesium, Mg, in Group 2 has two electrons in its outer energy level. Magnesium can lose these two electrons and
achieve a completed energy level.
Oxygen, O, in Group 16 has six electrons in its outer energy level. Oxygen can gain two electrons and achieve a
completed energy level.
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The two electrons, in magnesiums outer energy level, can be gained by two chlorine atoms.
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The two electrons, in magnesiums outer energy level, can be gained by two chlorine atoms.
The two negatively charged chloride ions are attracted to the positively charged magnesium ion forming ionic bonds.
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The two electrons, in magnesiums outer energy level, can be gained by two chlorine atoms.
The two negatively charged chloride ions are attracted to the positively charged magnesium ion forming ionic bonds.
The compound magnesium chloride (MgCl2) is produced.Monday, July 9, 2012
The two electrons, in magnesiums outer energy level, can be gained by two chlorine atoms.
The two negatively charged chloride ions are attracted to the positively charged magnesium ion forming ionic bonds.
The compound magnesium chloride (MgCl2) is produced.Monday, July 9, 2012
3.Pooling
Electrons
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Swimming in a Pool of Metal
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Metallic Bonding - Pooling
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Metallic Bonding - Pooling
We have just looked at how metal atoms form ionic bonds with atoms of nonmetals.
Monday, July 9, 2012
Metallic Bonding - Pooling
We have just looked at how metal atoms form ionic bonds with atoms of nonmetals.
Metals can form bonds with other metal atoms, but in a different way.
Monday, July 9, 2012
Metallic Bonding - Pooling
We have just looked at how metal atoms form ionic bonds with atoms of nonmetals.
Metals can form bonds with other metal atoms, but in a different way.
In a metal, the electrons in the outer energy levels of the atoms are not held tightly to individual atoms. Instead, they move freely among all the ions in the metal, forming a shared pool of electrons.
Monday, July 9, 2012
Metallic Bonding - Pooling
We have just looked at how metal atoms form ionic bonds with atoms of nonmetals.
Metals can form bonds with other metal atoms, but in a different way.
In a metal, the electrons in the outer energy levels of the atoms are not held tightly to individual atoms. Instead, they move freely among all the ions in the metal, forming a shared pool of electrons.
Metallic bonds form when metal atoms share their pooled electrons.
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Metallic Bonding - Pooling
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This bonding affects the properties of metals.
Metallic Bonding - Pooling
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This bonding affects the properties of metals. For example, when a metal is hammered into sheets or
drawn into a wire, it does not break. Instead, layers of atoms slide over one another.
Metallic Bonding - Pooling
Monday, July 9, 2012
This bonding affects the properties of metals. For example, when a metal is hammered into sheets or
drawn into a wire, it does not break. Instead, layers of atoms slide over one another.
An ounce of gold can be stretched into a wire 50 miles long.
Metallic Bonding - Pooling
Monday, July 9, 2012
This bonding affects the properties of metals. For example, when a metal is hammered into sheets or
drawn into a wire, it does not break. Instead, layers of atoms slide over one another.
An ounce of gold can be stretched into a wire 50 miles long.
Metallic Bonding - Pooling
Monday, July 9, 2012
This bonding affects the properties of metals. For example, when a metal is hammered into sheets or
drawn into a wire, it does not break. Instead, layers of atoms slide over one another.
An ounce of gold can be stretched into a wire 50 miles long.
A lump of pure gold the size of a matchbox can be flattened into a sheet the size of a tennis court.
Metallic Bonding - Pooling
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Metallic Bonding - Pooling
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The pooled electrons tend to hold the atoms together.
Metallic Bonding - Pooling
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The pooled electrons tend to hold the atoms together.
Metallic bonding also is the reason that metals conduct electricity well.
Metallic Bonding - Pooling
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The pooled electrons tend to hold the atoms together.
Metallic bonding also is the reason that metals conduct electricity well.
The outer electrons in metal atoms readily move
from one atom to the next to transmit current.
Metallic Bonding - Pooling
Monday, July 9, 2012
The pooled electrons tend to hold the atoms together.
Metallic bonding also is the reason that metals conduct electricity well.
The outer electrons in metal atoms readily move
from one atom to the next to transmit current.
Metallic Bonding - Pooling
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4.Sharing
Electrons
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Covalent Bonds - Sharing
Monday, July 9, 2012
Covalent Bonds - Sharing
Some atoms are unlikely to lose or gain electrons because the number of electrons in their outer levels makes this difficult.
Monday, July 9, 2012
Covalent Bonds - Sharing
Some atoms are unlikely to lose or gain electrons because the number of electrons in their outer levels makes this difficult.
Carbon has six electrons, four of the six electrons are in its outer energy level.
Monday, July 9, 2012
Some atoms are unlikely to lose or gain electrons because the number of electrons in their outer levels makes this difficult.
Carbon has six electrons, four of the six electrons are in its outer energy level.
Covalent Bonds - Sharing
Monday, July 9, 2012
Some atoms are unlikely to lose or gain electrons because the number of electrons in their outer levels makes this difficult.
Carbon has six electrons, four of the six electrons are in its outer energy level.
To obtain a more stable structure, carbon would either have to gain or lose four electrons.
Covalent Bonds - Sharing
Monday, July 9, 2012
Some atoms are unlikely to lose or gain electrons because the number of electrons in their outer levels makes this difficult.
Carbon has six electrons, four of the six electrons are in its outer energy level.
To obtain a more stable structure, carbon would either have to gain or lose four electrons.
This is difficult because gaining & losing so many electrons takes so much energy.
The alternative is sharing electrons.
Covalent Bonds - Sharing
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The Covalent Bond
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The Covalent BondThe chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond.
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The Covalent BondThe chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond. Shared electrons are attracted to the nuclei of both
atoms.
Monday, July 9, 2012
The Covalent BondThe chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond. Shared electrons are attracted to the nuclei of both
atoms. They move back and forth between the outer energy
levels of each atom in the covalent bond.
Monday, July 9, 2012
The Covalent BondThe chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond. Shared electrons are attracted to the nuclei of both
atoms. They move back and forth between the outer energy
levels of each atom in the covalent bond.
Each atom has a stable outer energy level some of the
time.
Monday, July 9, 2012
The Covalent BondThe chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond. Shared electrons are attracted to the nuclei of both
atoms. They move back and forth between the outer energy
levels of each atom in the covalent bond.
Each atom has a stable outer energy level some of the
time.Covalently bonded compounds are called molecular
compounds.Monday, July 9, 2012
The Covalent Bond
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The Covalent Bond
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The atoms in a covalent bond form a neutral particle.
The Covalent Bond
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The atoms in a covalent bond form a neutral particle.
The neutral particle formed when atoms share electrons is called a molecule.
The Covalent Bond
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The atoms in a covalent bond form a neutral particle.
The neutral particle formed when atoms share electrons is called a molecule.
The Covalent Bond
Monday, July 9, 2012
The atoms in a covalent bond form a neutral particle.
The neutral particle formed when atoms share electrons is called a molecule.
No ions are involved in covalent bonding because no electrons are gained or lost. Ionic compounds, such as sodium chloride (NaCl), are not referred to as molecules, because their basic units are
ions, not molecules.
The Covalent Bond
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Double and Triple Bonds
Monday, July 9, 2012
Double and Triple Bonds
Sometimes an atom shares more than one electron with another atom.
Monday, July 9, 2012
Double and Triple Bonds
Sometimes an atom shares more than one electron with another atom.
When two pairs of electrons are involved in a
covalent bond, the bond is called a double bond.
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Double and Triple Bonds
Monday, July 9, 2012
Double and Triple Bonds
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Double and Triple Bonds
Monday, July 9, 2012
Double and Triple Bonds
Monday, July 9, 2012
Double and Triple Bonds
Monday, July 9, 2012
Double and Triple Bonds
Monday, July 9, 2012
Double and Triple Bonds
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Double and Triple Bonds
Monday, July 9, 2012
Double and Triple Bonds
Monday, July 9, 2012
Double and Triple Bonds
Monday, July 9, 2012
Double and Triple Bonds
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Double and Triple Bonds
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Double and Triple Bonds
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Double and Triple Bonds
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Here is the sharing of three pairs of electrons between two nitrogen atoms in the nitrogen molecule.
Double and Triple Bonds
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Here is the sharing of three pairs of electrons between two nitrogen atoms in the nitrogen molecule.
When three pairs of electrons are shared by two atoms, the bond is called a triple bond.
Double and Triple Bonds
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Here is the sharing of three pairs of electrons between two nitrogen atoms in the nitrogen molecule.
When three pairs of electrons are shared by two atoms, the bond is called a triple bond.
Double and Triple Bonds
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Ionic vs. Covalent
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Polar and Nonpolar Molecules
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Polar and Nonpolar Molecules
Do atoms always share their electrons equally?
Monday, July 9, 2012
Polar and Nonpolar Molecules
Do atoms always share their electrons equally?The answer is no.
Monday, July 9, 2012
Polar and Nonpolar Molecules
Do atoms always share their electrons equally?The answer is no.
Some atoms have a greater attraction for
electrons than others do.
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Polar and Nonpolar Molecules
Do atoms always share their electrons equally?The answer is no.
Some atoms have a greater attraction for
electrons than others do.
Why?????
Monday, July 9, 2012
Polar and Nonpolar Molecules
Do atoms always share their electrons equally?The answer is no.
Some atoms have a greater attraction for
electrons than others do.
Why?????
Some atoms have more protons, therefore more
positive pull on the electrons.
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Polar and Nonpolar Molecules
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Chlorine attracts electrons more strongly than hydrogen does.
Polar and Nonpolar Molecules
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Chlorine attracts electrons more strongly than hydrogen does.
When hydrogen and chlorine covalently bond, the shared pair of electrons tends to spend more time near the chlorine atom than the hydrogen atom.
Polar and Nonpolar Molecules
Monday, July 9, 2012
Chlorine attracts electrons more strongly than hydrogen does.
When hydrogen and chlorine covalently bond, the shared pair of electrons tends to spend more time near the chlorine atom than the hydrogen atom.
Chlorine - 17 protons Hydrogen - 1 proton
Polar and Nonpolar Molecules
Monday, July 9, 2012
Chlorine attracts electrons more strongly than hydrogen does.
When hydrogen and chlorine covalently bond, the shared pair of electrons tends to spend more time near the chlorine atom than the hydrogen atom.
Chlorine - 17 protons Hydrogen - 1 proton
Polar and Nonpolar Molecules
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Polar and Nonpolar Molecules
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The unequal sharing makes one side of the bond more negative than the other. Such bonds are called polar bonds.
Polar and Nonpolar Molecules
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The unequal sharing makes one side of the bond more negative than the other. Such bonds are called polar bonds.
A polar bond is a bond in which electrons are
shared unevenly.
Polar and Nonpolar Molecules
Monday, July 9, 2012
The unequal sharing makes one side of the bond more negative than the other. Such bonds are called polar bonds.
A polar bond is a bond in which electrons are
shared unevenly.
Polar and Nonpolar Molecules
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Water
The bonds between the oxygen atom and hydrogen atoms in the water molecule are another example of polar bonds.
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“Get Away, Water!”
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When water molecules are exposed to a negative charge, the water molecules line up like magnets
with their positive ends facing the negative charge.
They are drawn to the negative charge on the balloon.
Water molecules also are attracted to each other. This attraction between water molecules accounts for many of the physical properties of water.
“Get Away, Water!”
Monday, July 9, 2012
“Get Away, Water!”
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Molecules that do not have these uneven charges are called nonpolar molecules.
“Get Away, Water!”
Monday, July 9, 2012
Molecules that do not have these uneven charges are called nonpolar molecules.
Because each element differs slightly in its ability to attract electrons, the only completely nonpolar bonds are bonds between atoms of the same element.
“Get Away, Water!”
Monday, July 9, 2012
Molecules that do not have these uneven charges are called nonpolar molecules.
Because each element differs slightly in its ability to attract electrons, the only completely nonpolar bonds are bonds between atoms of the same element.
One example of a nonpolar bond is the triple bond in the nitrogen molecule.
“Get Away, Water!”
Monday, July 9, 2012
Molecules that do not have these uneven charges are called nonpolar molecules.
Because each element differs slightly in its ability to attract electrons, the only completely nonpolar bonds are bonds between atoms of the same element.
One example of a nonpolar bond is the triple bond in the nitrogen molecule.
“Get Away, Water!”
Monday, July 9, 2012
Chemical Shorthand
In medieval times, alchemists were the first to explore the world of chemistry.
They used symbols to represent elements.
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Symbols for Atoms
Modern chemists also use symbols to represent elements.
The symbols are universal.
Each element is represented by a one letter-, two letter-, or three-letter symbol.
Many symbols are the first letters of the element’s name, such as H for hydrogen and C for carbon.
Others are the first letters of the element’s name in another language, such as K for potassium, which stands for kalium, the Latin word for potassium.
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Symbols for Compounds
Compounds can be described using element symbols and numbers. The figure below shows how two hydrogen atoms join together in a covalent bond.
The resulting hydrogen molecule is represented by the symbol H2. The subscript 2 means that two atoms of hydrogen are in the molecule.
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Don’t get confused!
2 H H2
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Chemical Formula
A chemical formula is a combination of chemical symbols and numbers that shows which elements
are present in a compound and how many atoms of each element are present.
When no subscript is shown, the number of atoms is understood to be one.
Monday, July 9, 2012
Chemical Formula
A chemical formula is a combination of chemical symbols and numbers that shows which elements
are present in a compound and how many atoms of each element are present.
When no subscript is shown, the number of atoms is understood to be one.
H2S
Monday, July 9, 2012
Chemical Formula
A chemical formula is a combination of chemical symbols and numbers that shows which elements
are present in a compound and how many atoms of each element are present.
When no subscript is shown, the number of atoms is understood to be one.
H2S Ag2S
Monday, July 9, 2012
Chemical Formula
A chemical formula is a combination of chemical symbols and numbers that shows which elements
are present in a compound and how many atoms of each element are present.
When no subscript is shown, the number of atoms is understood to be one.
H2S Ag2S NH3
Monday, July 9, 2012
Chemical Formula
A chemical formula is a combination of chemical symbols and numbers that shows which elements
are present in a compound and how many atoms of each element are present.
When no subscript is shown, the number of atoms is understood to be one.
H2S Ag2S NH3
H2SO4Monday, July 9, 2012
Chemical Formula
A chemical formula is a combination of chemical symbols and numbers that shows which elements
are present in a compound and how many atoms of each element are present.
When no subscript is shown, the number of atoms is understood to be one.
H2S Ag2S NH3
H2SO4 NaOHMonday, July 9, 2012
Chemical Formula
A chemical formula is a combination of chemical symbols and numbers that shows which elements
are present in a compound and how many atoms of each element are present.
When no subscript is shown, the number of atoms is understood to be one.
H2S Ag2S NH3
H2SO4
H2SNaOH
Monday, July 9, 2012