Atoms and Their Interactions

1. Atoms and Their Interactions 6.1

2. Elements • Elements • A substance that can not be broken down into simpler chemical substances • The Periodic Table lists all known elements

3. Atoms: The Building Blocks of Elements • Atom • Smallest particle of an element that has the characteristics of that element • Structure of an Atom • Nucleus • Protons (Positive) • Neutrons (Neutral) • Energy levels (outside of the nucleus) • Electrons (Negative)

4. How come atoms do NOT have a charge? • In an atom, the number of electrons equals the number of protons. • So the number of positive and negative charges balance out, giving the atom a charge of 0.

5. Fill in the following chart:

6. Energy Levels • First energy level • 2 electrons • Second energy level • 8 electrons • Third energy level • 18 electrons Rules for filling in energy levels! • The first energy level has to be FULL before electrons can go into the 2nd energy level • The 1st and the 2nd energy level has to be FULL before electrons can go into the 3rd energy level

7. Compounds • Compounds are substances made of 2 or more elements that form a molecule (2 or more atoms together). • Examples of common compounds: • Table Salt - NaCl • Oxygen gas – O2 • Water – H2O

8. Properties of Compounds • Compounds have BONDS between the atoms • It is difficult to separate the parts of a compound • Compounds have chemical formulas to tell you what elements are found in the compound and how many atoms of each element are present. • The chemical formula for water is H2O. There are two atoms of hydrogen and one of oxygen.

9. Ionic Bonds Form when electrons are exchanged between atoms. Covalent Bonds Form when electrons are shared between atoms. Ionic Vs. Covalent Bonds Both types of bonds result in all atoms having a full outer energy level.

10. Chemical Reactions • Chemical reactions happen when bonds are formed or broken and recombine to form new compounds • All chemical reactions that occur within an organism are referred to as that organism’s metabolism.

11. Mixtures • Mixtures are combinations of 2 or more pure substances or compounds • Some common mixtures: • Iced Tea • Dirt • Paint

12. Properties of Mixtures • There are NO BONDS holding mixtures together • Mixtures can often be separated • Mixtures can occur in any proportions and DO NOT HAVE A SET FORMULA and can use different components

13. Solutions Solution – mixture of one or more substances uniformly distributed in another substance. Can be solid, liquid, gas ex. Plasma (liquid) brass (solid) copper and zinc soda (liquid/gas) water and CO2

14. Acids & Bases The Homeostasis of living things depends on the degree of acidity (acid) and alkalinity (base) in certain areas

15. Acids & Bases Acids= any substance that forms hydrogen (H+) in water. Alkalinity (a/k/a basic solution)= any substance that forms hydroxide ions (OH-) in water

16. Acids - pH < 7 • Sour taste • Corrosive on metals • Burns skin • Ex. Orange juice, • vinegar, sulfuric acid *Homeostasis relevance - your stomach must have a certain acidity to function properly

17. Bases -pH > 7 • Tastes bitter • Slippery • Irritate the skin • Ex. NaOH • Homeostasis relevance- • your small intestine needs a certain alkalinity (basic) to function properly

18. Tells you how acidic or basic something is Ranges 0-14 7 = neutral above 7 = base below 7 = acid Ten fold system Measure pH with litmus paper pH Scale