1. Structure of Atoms

2. Atom- Basic unit of matter
Nucleus- center of the atom
Proton- Positive Particle
Neutron- Neutral Particle
Electron - Negative Particle

3. Atomic number = number of protons
Number of protons = number of electrons

4. Atomic Mass/Weight= Neutrons + Protons
So… Neutrons = Atomic Mass – Atomic #
Ex – 6 =
6 neutrons
You have to round the
Atomic mass to the
Nearest whole number

5. -Electrons orbit the nucleus
-The first orbit holds two electrons
-The second orbit holds eight electrons
-The third orbit holds eight electrons

6. Electrons in the outer most orbital are called valence electrons

7. Compound- Substance formed by the chemical combination of two or more elements in definite proportions

8. Element A pure substance that consists entirely of one type of atom
Ex-
Hydrogen (all atoms have 1 electron)
Calcium (all atoms have 20 electrons)
Gold (all atoms have 79 electrons)

9. Chemical Bonds

10. Ion An atom that has a positive or negative charge
How can this happen?
What would have to change for an atom to become an ion?

11. Chemical Bonds Sodium Chlorine Table
Metal Gas Salt
1. Ionic- bond formed when one or more electrons are transferred from one atom to another
(two or more ions attracted to one another b/c of opposite charges)

12. Ionic Bond Properties
Molecules with Ionic bonds have crystal lattice structures
High melting and boiling points
Tend to be brittle solids
Are dissolved (soluble) in water
Conduct electricity well

13. Covalent- bond formed when electrons are shared between atoms

14. Covalent Bond Properties
Stronger than ionic bonds
Often in gases, liquids, or soft solids
Poor conductors of heat and electricity
Low melting and boiling points

15. Metallic Bonding
the covalent bonding between atoms in metals, in which the valence electrons are free to move through the crystal.
Electrons are shared between atoms
Very strong bonds
Conduct heat and electricity well

16. Van der Waals Forces- slight attraction between nearby atoms

17. Chemical Reaction-
changes one set of chemicals to another by changing bonds
Reactant- elements or compounds going into reaction
Product- elements or compounds coming out of reaction
2H2 + O2 → 2H20
H and O are reactants
H2O is the product

18. Reactions can be Reversible
CO2 + H2O H2CO3
H2CO CO2 + H2O
How many atoms of oxygen are in the products of the second reaction?
How many molecules of carbon are in the products of the first reaction?

19. Weekend Write #2
A. How is a car like a living organism? As Biologists, why do we consider a car to be nonliving?
B. Explain how elements are different from compounds and give 2 examples of each.

20. Finished? Rewrite Weekend Write #1
Finish flashcards that were due today
Study for quiz on Tuesday (scientific method, characteristics of life, chemistry)
Read section 2-3 in the text book