1. Atoms Atom – smallest particle of an element that retains the characteristics of that element. Element – the most simple chemical substance Arranged in the periodic table –Columns and rows –Each element is identified via 1 letter or 2 letter abbreviation

2. Structure of an Atom Composed of a Nucleus –Contains Protons (p+)‏ –Contains Neutrons (n0)‏ –Protons + Neutrons = Atomic Mass –# protons = atomic number Surrounded by Electrons (smaller particles) with negative (e-) charges. –Travel in regions called energy levels 2 in 1 st shell 8 in 2 nd shell 18 in 3 rd shell

3. Crash course on the Periodic Table Columns go up and down Rows go left and right Metals are left of the zigzag, Nonmetals to the right (except H)‏ Elements are uncharged, which means the number of protons MUST EQUAL the number of electrons Column numbers tell you valence shell electron number (I.e. their bonding pattern)‏ Valence shell electrons are the outermost electrons on an atom. –Hydrogen 1, 1 valence e- –Oxygen 16, 6 valence e- –Carbon 14, 4 valence e- –Nitrogen 15, 5 valence e- What element am I? _____________________atom am I?

4. Bonding - Ionic Elements become “happy” when they have a full valence electron shell –2, 8, 18, etc With elements only 1 or 2 electrons away from a full shell will lose or gain electrons. Bonds between metals and nonmetals. The charge between the elements keeps them attracted together (ions)‏ Compound – atoms held together by ionic bonds.

5. Common Bonds in Biology Covalent Bonds are the most common in Biology. Organic in biology means “made of Carbon.” Isotopes – atoms of the same element that contain different numbers of neutrons.

6. Bonding - Covalent When elements have about 4 electrons to gain or lose, they elect to share electrons! –Saves energy, easier to do than to steal! Occurs between nonmetals. Water uses covalent bonds. Molecule – atoms held together by covalent bonds.

7. Properties of Water Consists of 1 Oxygen atom and 2 Hydrogen atoms per 1 water molecule. Water resists temperature change (insulator)‏ Has three phases: –Solid (ice), liquid, gas (vapor)‏ Carries substances via Osmosis. –Serves as material transportation –Blood, plant sap Water makes up 70-95% of organisms. Cycles through the kidneys and eliminated out of the body

8. Hydrogen Bonds Water – a polar molecule –Means it has a slightly positive (+) end and a slightly negative (-) end. Because of its polarity… Bonds to other water molecules through Hydrogen Bonds - Holds large molecules like proteins together Sticks together (+ and – attract) to create a cohesion via surface tension Good solvent Can adhere creep up tubes via capillary action. - From ground to tops of trees. - The meniscus in a graduated cylinder

9. Mixtures A mixture is a combination of substances where both substances keep their original properties. –Physically mixed, not chemically mixed. Solution – one or more substances (solutes) are distributed evenly in another substance (solvent) (water)‏ –The more solute in a solvent, the higher the concentration. –Organisms need to maintain a certain concentration for life processes, called homeostasis. Suspensions – mixtures of water and non dissolved particles –Example: Blood

10. pH Scale pH – a measure of how acidic or basic something is. Use pH paper to test Acidic range is 0-6 –Acids form H+ ions in water –Example: Lemon (2)‏ Neutral is 7 –Example: Pure water and blood (7)‏ Basic range 8-14 –Bases form OH- ions in water –Example: Ammonia (12)‏ Buffers – weak acids and weak bases that react with strong acids or bases to prevent sudden changes in pH. Neutralization reaction: –HCl + NaOH → HOH + NaCl