1. The Atom

2. What is an Atom? Atom: Smallest unit of all matter 3 Main Parts:
1) Proton (+ charge)
2) Neutron (No charge)
3) Electron (- charge)
Protons & Electrons usually equal in number
Elements (substance made of only 1 type of atom) are identified on the Periodic Table

3. Reading the Periodic Table
Atomic Number: Number of protons the atom contains
Usually # of electrons also
Atomic Mass: Combined # of protons and neutrons inside the nucleus
Electrons too small to affect mass
How many protons, electrons, and neutrons does Carbon contain?
Protons = ______
Electrons = ______
Neutrons = ______ 6 6 6

4. What’s the: Atomic number of Beryllium? B) Atomic mass of Beryllium? 4
C) How many protons?
D) How many electrons?
E) How many neutrons? 4 9 4 4 5

5. Electron Cloud Electrons orbit the nucleus in “energy levels”
1st level:
closest to nucleus
stable w/ 2 electrons
2nd level:
stable w/ 8 electrons
3rd level:
Atoms are stable when the outermost level is “full”
Examine Carbon below. It has 2 electrons in the first level and 4 electrons in the 2nd level. Is Carbon stable?

6. Molecules Molecule: 2 or more atoms held together by a covalent bond
Form when atoms are unstable
Covalent Bond: Chemical bond where atoms share electrons
Ex: Oxygen atom
Why unstable? Only 6 electrons in outer energy level
What happens? Each oxygen atom will share two electrons with the other oxygen
End result? Both will have 8 electrons in its outer level (O2 is created)
Molecules

7. Ionic Bonds Ionic bond: chemical bond where electrons are gained/lost
sodium
chlorine
Ionic bond: chemical bond where electrons are gained/lost
Creates Ions (atoms with + or – charge)
Held together by magnetic attraction
Cause: 1 atom steals an electron(s) from another atom
Ex: Sodium + Chlorine = Sodium Chloride

8. Ionic Bonds 11+ 17+ 11+ 17+ 10- 18- 11- 17- +1 -1 Na Cl Na Cl e e e e
sodium e e e e e e
chlorine e e e e e e e e e
After bonding
Before bonding Na Cl
Protons (+)
Electrons (-)
Net charge Na Cl
Protons (+)
Electrons (-)
Net charge
11+
17+
11+
17+
10-
18-
11-
17- +1 -1

9. Kobe Kuiz Name the 3 subatomic particles.
Which subatomic particles are found inside the nucleus?
The atomic number usually allows us to determine the amount of which two subatomic particles?
If an atom has the atomic mass of 14 and the atomic number of 6, how many protons, neutrons, and electrons does the atom contain?
After an ionic bond is formed, what is the charge of the atom that gained an electron?
Which type of chemical bond shares electrons?