Atom• Basic unit of matter

Subatomic particles• Protons - • Neutrons - • Electrons -

Positively charged (+)

Not charged (neutral)

Negatively charged (-)

Bind together to form the nucleus

Electrons Protons

Neutrons

Nucleus

Element• A pure substance that consists

of just one type of atom

6

CCarbon12.011

Atomic number

An elements atomic number = number of protons

Isotope• Atoms of the same element

that differ in the number of neutrons they contain

Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14

6 electrons6 protons6 neutrons

6 electrons6 protons8 neutrons

6 electrons6 protons7 neutrons

6

CCarbon12.011 Mass number

The Sum of protons and neutrons in the nucleus of an atom is its mass number

Atomic Mass

• The weighted average of the masses of an elements isotope is called its atomic mass

Radioactive isotopes• Can be dangerous

• Can be used practically–Radioactive dating

–Treat cancer

–Kill bacteria

Compounds• A substance formed by the

chemical combination of two or more elements in definite proportions

• Ex) H2O, NaCl

Table Salt

Ionic Bonds• Formed when one or more

electrons are transferred from one atom to another

Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-)

Transferof electron

Protons +11Electrons -11Charge 0

Protons +17Electrons -17Charge 0

Protons +11Electrons -10Charge +1

Protons +17Electrons -18Charge -1

• If an atom loses an electron it becomes positive

• Ex: All metals

• If an atom gains an electron it becomes negative

• Ex:All nonmetals

Ions• Positively and negatively

charged atoms

Covalent Bonds• Forms when electrons are

shared between atoms

Molecule• The structure that results when

atoms are joined together by a covalent bond

• Both elements are nonmetals

• Smallest unit of most compounds

Van der Waals Forces• A slight attraction that

develops between the oppositely charged regions of nearby molecules due to unequal sharing of electrons

Homework

Questions and Answers

1. Describe the structure of an atom.

Atoms are made up of protons and neutrons in a nucleus. Electrons are in constant motion in the space around the nucleus.

2. Why do all isotopes of an element have the same chemical properties

They have the same number of electrons

3. What is a covalent bond?

A bond formed when electrons are shared between atoms

4. What is a compound? How are they related to molecules

A compound is a substance formed by the chemical combination of two or more elements in definite proportions. A molecule is the smallest unit of most compounds

5. How do Van der Waals forces hold molecules together?

When the sharing of electrons are unequal, a molecule has regions that are charged. An attraction can occur between oppositely charged regions of nearby molecules

6. How are ionic bonds and Van der Waals forces similar? How are they different?

In both cases, particles are held together by attractions between opposite charges. The difference is that ionic charges are stronger

Section 2: Properties of Water

Objectives• Why are water molecules polar?

• What are acidic solutions? What are basic solutions?

Basic information about water

• Formula for water: H2O

• Structure of a water molecule:

• The solid lines between the O and the H

represent covalent bonds• In covalent bonds, electrons between

the atoms are shared.

• In some kinds of molecules, the electrons

• are shared equally between two atoms.

6. We say that those are nonpolar covalent bonds.

• In water, though, oxygen and hydrogen

do NOT share their electrons equally with each other so we say that there is a polar covalent bond between them.

• Because the oxygen atom is pulling negative charges toward itself, this makes oxygen take on a partial negative charge.

• 9. The hydrogen atom is having negative

• electrons pulled away from it, so the • 2 hydrogen atoms will take on a partial• positive charge.

• When another water molecule comes in, the partial negative oxygen of one water molecule will hydrogen bond with the partial positive hydrogen of another water molecule.

• 11. Hydrogen bonds are very weak, but • they are very important in molecules like DNA and

proteins.

• Hydrogen bonds are also responsible for the many properties of water, such as: A. Cohesion:

the attraction of molecules of the same kind (water molecules to other water molecules)

B. Adhesion: the attraction among molecules of different substances

(water molecule to something else)

The Big Idea

• Much of our planet is covered in water

• Water is necessary for life to exist• If life exists on other planets, there

most likely is water present• Water has many properties that

make life possible

Polarity(-)

(+)

The oxygen atom has a stronger attraction for electrons

Hydrogen Bonds• Because of waters partial charges,

they can attract each other and create hydrogen bonds

• Not as strong as covalent or ionic bonds

• Waters ability to create multiple hydrogen bonds gives it many special properties

Cohesion• Attraction between molecules of

the same substance

Adhesion• Attraction molecules of different

substances

Mixture• Material composed of two or more

elements or compounds that are physically mixed but not chemically combined

• Ex.) salt & pepper, earths atmosphere

Solutions• Mixture of two or more

substances in which the molecules are evenly distributed

• Ex.) salt water

• Settles out over time

Solutions

Cl-

Water

Cl-

Na+

Water

Na+

Solute• Substance that is dissolved

• Ex.) salt

Solvent• The substance that does the

dissolving

• Ex.) Water

Suspensions• Mixture of water and non-

dissolved materials

• Separate into pieces so small, they never settle out

• Ex: water and oil

Types of solutions• A dilute solution is weak solution• A concentrated solution is strong.• An unsaturated solution contains less

dissolved solute than it can hold at a given temp.

• A saturated solution contains all of the solute it can hold at a given temp.

• A Super saturated solution containing more solute than it can normally hold at a given temp.

( Crystals are often seen in this type of solution).

What is the pH scale?

• measure of the concentration of hydrogen ions in a solution

• Always shows reading between 0-14• pH between 0-7 is an acid• pH between 7-14 is a base• pH 7 is neutral. • neutral: neither acidic nor basic

*Tastes sour*Conducts electricity

*Corrosive to skin*Can eat through metal

*Formulas starts with “H”*Always releases hydrogen ions (H+)

when dissolved in water*pH is between 0-7

What is an acid?

*Tastes Bitter*Conducts electricity

*Corrosive to skin*Feel slippery

*Formulas ends with “OH”*Always releases hydroxide ions (OH¯) when dissolved in water

*Red litmus paper into Blue (indicator)

*pH between 7-14

What is a base?

What are indicators?

• substance that changes color in an acid or a base

What is neutralization?

• reaction between an acid and a base to produce a salt and water

What is an electrolyte?

• electrolyte : substance that conducts an electric current when it is dissolved in water

• ionization : formation of ions

• Nonelectrolyte: substance that will not conduct an electric current when it is dissolved in water .

Neutral

Acid

Base

Buffers• Weak acids or bases that can

react with strong acids or bases to prevent sharp, sudden pH changes

Homework

Questions and Answers

1. Use the structure of a water molecule to explain why its polar

Oxygen atom has greater attraction for electrons, therefore the oxygen atom is negative and the hydrogen end is positive

2. Compare acidic and basic solutions in terms of their H+ ion and OH- ion concentrations

Acid have more H+ ions than OH-

ions, and bases have more OH-

ions than H+ ions

3. What is the difference between a solution and a suspension?

In a solution, all components are evenly distributed. In a suspension, un-dissolved particles are suspended

4. What does pH measure?

The concentration of H+ ions in a solution

5. The strong acid hydrogen floride (HF) can be dissolved in pure water. Will the pH of the solution be greater or less than 7?

less than 7

Section 3: Carbon Compounds

Objective• What are the functions of each

group of organic compounds?

• Most of the compounds that make up living things contain carbon. In fact, carbon makes up the basic structure, or “backbone,” of these compounds. Each atom of carbon has four electrons in its outer energy level, which makes it possible for each carbon atom to form four bonds with other atoms.

• As a result, carbon atoms can form long chains. A huge number of different carbon compounds exist. Each compound has a different structure. For example, carbon chains can be straight or branching. Also, other kinds of atoms can be attached to the carbon chain.

Section 2-3

Interest Grabber

Life’s backbone

Methane Acetylene Butadiene Benzene Isooctane

Macromolecules “giant molecules”

• Formed by a process called polymerization

Monomers• Smaller units

Polymers• Linked up monomers

Carbohydrates• Compounds made up of carbon,

hydrogen, and oxygen atoms usually in a ratio of 1:2:1

• Main source of energy

• The monomers of starch are sugars

• Single sugar molecules are called monosaccharides

• The large macromolecules formed from monosaccharides are known as polysaccharides

Starch

Glucose

Lipids• Made mostly from carbon and

hydrogen atoms

• Used to store energy

Lipid Glycerol

Fatty Acids

Proteins• Macromolecules that contain

nitrogen as well as carbon, hydrogen, and oxygen

• Proteins are polymers of molecules called amino acids

Amino Acids

General structure Alanine Serine

Carboxyl group

• More than 20 different amino acids, can join to any other amino acid

• The instructions for arranging amino acids into many different proteins are stored in DNA

• Each protein has a specific role• The shape of proteins can be very

important

Proteins

Amino Acids

Nucleic Acids• Macromolecules containing hydrogen,

oxygen, nitrogen, carbon, and phosphorus

Double Helix

Nucleotides• Consists of 3 parts: 5-carbon sugar,

phosphate group and nitrogen base

Nitrogen Base

5-Carbon Sugar

Phosphate group

2 kinds of nucleic acids• RNA (ribonucleic acids) –

contains sugar ribose

• DNA (deoxyribonucleic acid) – contains sugar deoxyribose

Homework

Questions and Answers

1. Name four groups of organic compounds found in living thingscarbohydrate, lipid, protein, nucleic acids

2. Describe at least one function of each group of organic compoundscarbohydrates – energylipids – store energyproteins – form tissuenucleic acids – transmit hereditary information

3. Compare the structures and functions of lipids and starches

Lipids are made from carbon and hydrogen. Starches are made of carbon, hydrogen and oxygen. They both can be used to store energy