Chemistry of Life

Chapter 3Pg. 48-73

Section 1: Matter and Substances

Key Ideas:

What makes up matter?

Why do atoms form bonds?

What are some important interactions between substances in living things?

What is Matter??? Matter is anything that has mass and

takes up space.

Atoms Atoms are the smallest units of matter

that still retain the properties of an element.

Atomic Structure

Particle Location Charge

Proton Inside the Nucleus

Positive (+)

Neutron Inside the Nucleus

No charge (neutral)

Electron Outside the Nucleus

Negative (-)

Element An element is a substance made up of

atoms that have the same number of protons. Example: How many protons do all Carbon

atoms have?

Example: How many protons do all Magnesium atoms have?

Element Configuration Atomic Number - The

number of protons in the nucleus of an atom

Atomic Mass Number - Total number of protons and neutrons

Atomic # 6

Symbol CAtomic Mass # 12.011

# of Neutrons = Atomic Mass # - Atomic #

Electron Energy Levels Electrons are located OUTSIDE of the

nucleus of an atom. Electrons are arranged in different energy levels.

1st Level: 2 electrons 2nd Level: 8 electrons 3rd Level: 18 electrons 4th Level: 32 electrons

Valence Electrons Valence electrons are those located in the

OUTERMOST energy level. Example: This is called a Bohr Model of an

atom. It shows ALL the electrons in the atom. Only the electrons on the outermost ring are the

valence electrons!!

Chemical Bonding Chemical bonds form between atoms and

hold the atoms together. Atoms are most stable (and happy) when they

have 8 valence electrons.

Covalent Bonding Covalent bonding is when atoms share

valence electrons. Example: A molecule is a group of atoms joined

together by covalent bonds. Water H20 is a covalent

compound

Ionic Bonding Ionic bonding occurs when atoms gain or

lose electrons in order to have 8 valence electrons. Ion- an atom that has a positive or negative charge because it lost or gained electrons. Example: Sodium + Chlorine

Polarity In covalent bonds, the shared electrons

are attracted more to one atom than the other. One end, or “pole” has a negative charge and the other end has a positive charge. Water is polar:

Solubility Water can dissolve polar molecules, like

sugar and salt. Non-polar substances, like oil, grease, and

wax do NOT dissolve in water. The reason: water molecules are more

attracted to themselves than to the non-polar molecules.

Section 2: Water and Solutions

Key Ideas:

What makes water a unique substance?

How does the presence of substances dissolved in water affect the properties of water?

Properties of Water Most of the unique properties of water

result because water molecules form hydrogen bonds with each other!

1. Ice floats- water is less dense as a solid than as a liquid!

Continued…Properties of Water 2. Water absorbs and retains heat.

Water can absorb large amounts of heat without changing temperature.

Water takes a long time to cool. Large bodies of water (oceans/lakes)not heating up or cooling too quickly keeps temperatures on earth from changing too fast.

Continued…Properties of Water 3. Water molecules stick to each

other!Hydrogen bonds hold water

molecules together.When you see a water drop, it

looks like a ball because the molecules stick together!

Cohesion is the attraction of particles of the same substance.

Continued…Properties of Water 4. Water molecules stick to other polar

substances (called adhesion!)

Solutions Solution is a mixture in which ions or

molecules of one or more substances are evenly distributed in another substance. Example: Dissolving salt in water makes a salt

water solution. The salt is dissolved evenly throughout the water.

Acids and Bases Acids- have a pH of 7 and lower (H30+ ions) Bases-have a pH of 7 and higher (OH- ions)

Water: pH is 7 (neutral) Acid + Base = water!!!

pH and Buffers pH is a measure of how acidic or basic a solution is.

pH of human blood is 7.4……if the pH goes too high (7.8) or too low (7.0) a human will die within minutes!!!

A buffer is a substance that prevents pH changes in a solution.

Section 3: Carbon Compounds

Key Ideas:What are chemicals of life made from?What is the role of carbohydrates in cells?What do lipids do?What determines the functions of proteins?What do nucleic acids do?

Biomolecules Biomolecules are the building blocks of

cells Basic units of biomolecules are atoms of

carbon.

4 Biomolecules of Living Organisms 1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic Acids

Carbohydrates Stores energy and provides shape to

organisms Starch

Potatoes & Plants Cellulose

One of the most abundant carbohydrates Makes up materials such as pencils, paper, and

desks Sugars

Mono-saccharide – Easily broken down for quick energy (Candy bar)

Di-saccharide- Two sugars (example table sugar) Polysaccharide – Combination of mono &

disaccharide’s (starch)

Lipids

Longer energy storage Include fats, oils, steroids, and waxes Functions in adaptation

Human Hormones Keeps whales warm Wax keeps fruit dry

Proteins Proteins are molecules made of amino acids.

There are 20 possible amino acids that join together in different combinations to form many different proteins.

Protein uses: Hair, skin, nails, ligaments, muscles,

Nucleic Acids