Atoms, Ions & Atoms, Ions & CompoundsCompounds

Unit 3Unit 3

Vocab Flash cardsVocab Flash cards

octet ruleoctet ruleion ion ionization energyionization energyelectromagnetismelectromagnetismLaw of Multiple ProportionsLaw of Multiple Proportionscationcationanionanionionic bondsionic bonds

Atomic Theory of MatterAtomic Theory of Matter

The theory that atoms The theory that atoms are the fundamental are the fundamental building blocks of building blocks of matter - John Dalton matter - John Dalton (early 1800’s).(early 1800’s).

Dalton’s PostulatesDalton’s Postulates

• All atoms of a given element are identical (same All atoms of a given element are identical (same size, mass and other properties) but atoms of one size, mass and other properties) but atoms of one element are different from the atoms of all other element are different from the atoms of all other elementselements• Atoms are neither created nor destroyed in Atoms are neither created nor destroyed in chemical reactions, simply rearranged. Atoms can chemical reactions, simply rearranged. Atoms can not be changed into different atoms by chemical not be changed into different atoms by chemical reactions.reactions.• Compounds are formed when atoms of more than Compounds are formed when atoms of more than one element combine; a given compound always has one element combine; a given compound always has the same ratio of atoms.the same ratio of atoms.

• Each element is composed of extremely small Each element is composed of extremely small particles called atoms.particles called atoms.

Daltons Atomic Theory Daltons Atomic Theory explains three laws.explains three laws.

The Law of Conservation of Mass.The Law of Conservation of Mass.

• The Law of Constant Composition

• The Law of Multiple Proportions

Law of Constant CompositionLaw of Constant CompositionJoseph ProustJoseph Proust (1754–1826) (1754–1826)

Also known as the law of definite proportions.Also known as the law of definite proportions.

The elemental composition of a pure The elemental composition of a pure substance never varies.substance never varies. Ex: HEx: H22O from Atlantic Ocean vs. Pacific OceanO from Atlantic Ocean vs. Pacific Ocean

The Law of Multiple The Law of Multiple ProportionsProportions

Two elements can be combined to form Two elements can be combined to form more than one compound.more than one compound.

The ratio of the masses is a small whole The ratio of the masses is a small whole number.number.

Law of Conservation of MassLaw of Conservation of Mass

The total mass of substances present The total mass of substances present at the end of a chemical process is the at the end of a chemical process is the same as the mass of substances present same as the mass of substances present before the process took place.before the process took place.

Octet RuleOctet Ruleatoms tend to gain, lose or share electrons so atoms tend to gain, lose or share electrons so as to have eight electrons in their outer electron as to have eight electrons in their outer electron shellshelltry to achieve the same configuration as the try to achieve the same configuration as the nearest noble gas nearest noble gas

IonsIons

When atoms lose or gain electrons, they When atoms lose or gain electrons, they become ions.become ions. Cations are positive and are formed by elements Cations are positive and are formed by elements

on the left side of the periodic chart.on the left side of the periodic chart. Anions are negative and are formed by elements Anions are negative and are formed by elements

on the right side of the periodic chart.on the right side of the periodic chart.

An Na1+ ion containing 11 protons and 12 neutrons would contain ___ electrons.

1. 10

2. 1

3. 12

4. 22

Correct Answer:

The +1 charge indicates there is 1 more proton than electrons:

11 1 = 10

1. 10

2. 1

3. 12

4. 22

Which of the following species has the greatest number of electrons?

1. Cl

• Ca2+

• P3

• K• Ar

Correct Answer:

K has 19 electrons; all the other species listed have only 18 electrons.

1. Cl

• Ca2+

• P3

• K• Ar

Ionic BondsIonic Bonds

Ionic compounds (such as NaCl) are Ionic compounds (such as NaCl) are generally formed between metals and generally formed between metals and nonmetals.nonmetals.

Ionization EnergyIonization Energy

The energy required to remove an electron The energy required to remove an electron from an atomfrom an atom First ionization energy is that energy required First ionization energy is that energy required

to remove first electron. to remove first electron. Energy + X Energy + X X X++ + electron + electron

Second ionization energy is that energy Second ionization energy is that energy required to remove second electron, etc.required to remove second electron, etc.

Energy + X Energy + X X X+2+2 + electron + electron

Ionization EnergyIonization Energy

It requires more energy to remove each It requires more energy to remove each successive electron.successive electron.

When all valence electrons have been When all valence electrons have been removed, the ionization energy takes a removed, the ionization energy takes a quantum leap.quantum leap.

Trends in First Ionization EnergiesTrends in First Ionization Energies

As one goes down a As one goes down a column, less energy column, less energy is required to remove is required to remove the first electron.the first electron. the valence electrons the valence electrons

are farther from the are farther from the nucleus.nucleus.

ElectronegativityElectronegativity

How strongly an atom attracts electronsHow strongly an atom attracts electrons

Fluorine has the highest electronegativity Fluorine has the highest electronegativity with the strongest attraction for electronswith the strongest attraction for electrons

Francium has the lowest electronegativityFrancium has the lowest electronegativity

Writing FormulasWriting Formulas

Because compounds are electrically neutral, Because compounds are electrically neutral, one can determine the formula of a one can determine the formula of a compound this way:compound this way: The charge on the cation becomes the subscript The charge on the cation becomes the subscript

on the anion.on the anion. The charge on the anion becomes the subscript The charge on the anion becomes the subscript

on the cation.on the cation. If these subscripts are not in the lowest whole-If these subscripts are not in the lowest whole-

number ratio, divide them by the greatest common number ratio, divide them by the greatest common factor.factor.

The compound, CuSO4, is called

1. Calcium sulfide2. Carbon sulfide3. Calcium sulfite4. Calcium sulfate5. Copper sulfate

Correct Answer:

The compound is ionic, derived from the copper(II) cation (Cu2+) and the sulfate anion (SO4

2).

1. Calcium sulfide2. Carbon sulfide3. Calcium sulfite4. Calcium sulfate5. Copper sulfate

The correct name for the compound, MgC2 is

1. Carbon magneside2. Magnesium carbide3. Magnesium carbonate4. Manganese dicarbide5. Magnesium dicarbide

Correct Answer:

In this unusual ionic compound, the cation is magnesium cation (Mg2+) and the anion is carbide or acetylide (C2

2).

1. Carbon magneside2. Magnesium carbide3. Magnesium carbonate4. Manganese dicarbide5. Magnesium dicarbide

The simplest chemical formula for the binary ionic compound CaxNy is

1. Ca2N2. Ca2N3

3. Ca3N2

4. Ca3N

Correct Answer:

Ca loses two electrons to become Ca2+, while N gains three electrons to become N3

. To be neutral, positive charges and negative charges have to balance.

1. Ca2N2. Ca2N3

3. Ca3N2

4. Ca3N