Chemistry of Life Chapter 3 Pg

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 ParticleLocationCharge ProtonInside the Nucleus Positive (+) NeutronInside the Nucleus No charge (neutral) ElectronOutside 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 C Atomic Mass # # 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. 1 st Level: 2 electrons 2 nd Level: 8 electrons 3 rd Level: 18 electrons 4 th 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 H 2 0 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 (H 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