1. Drawing Atoms & Chemical Bonding
May 19, 2019

2. Electron Energy Levels
Electrons are arranged in within the electron cloud.
Each energy level can hold a certain maximum number of electrons.
First level – ____
Second level – ____
Third level – ____ 2 8 8

3. Drawing an Atom Fluorine Atom (F)
How many electrons does a Fluorine atom have? _______
9 P
10 N 9

4. Electron Energy Levels
Valence
Electron Energy Levels
most stable
The atoms have the outermost energy level filled.
Atoms in which the outermost energy level is filled does not easily gain or lose electrons, therefore they do not easily form compounds with other elements.
____________ electrons represent the number of electrons in the outer energy level.

5. Go away, I don’t want to BOND with anyone.
Drawing an Atom
I’m Stable
Neon Atom (Ne)
How many electrons does a Neon atom have? _______
10 P
10 N
Go away, I don’t want to BOND with anyone. 10

6. CHEMICAL BONDS
When two or more elements come together, they form a compound.
Compounds are held together by forces called chemical bonds.
Atoms can form chemical bonds by sharing electrons or by transferring electrons from one atom to another.

7. Types of Bonds
When a compound is formed through the transfer of electrons, this is called an ionic bond.
Most ionic compounds are formed by the transfer of electrons from a metal to a nonmetal.
When an atom loses an electron to move to another atom, it ends up with more protons than electrons. This results in an overall __________ charge.
positive

8. Types of Bonding negative
When an atom gains an electron from another atom, it ends up with more electrons with protons. This results in an overall ___________ charge.
Ions – electrically charged atoms.
(Ex) Na+ or Cl-
negative

9. Now, the Na gives or transfers its one extra electron to Cl
Cl Na
Now, the Na gives or transfers its one extra electron to Cl
11P
12N
17P
18N
Now everyone is happy

10. Types of Bonding
Covalent bond – a bond based on the attraction between atoms that share electrons (Ex) Water –H2 O

11. Covalent Bonding (Water Molecule)
H2O
1 P
Hydrogen
8 P
8 N
Hydrogen
1 P
Oxygen

12. Review Questions
In water, how many electrons does oxygen share with each hydrogen atom?
What kind of bond is this?
How many valence electrons does sodium have?
How many valence electrons does chlorine have?
Describe what happens when sodium bonds with chlorine.
One
Covalent Bond
One
Seven

13. Review Questions What kind of bond is formed between Na and Cl?
After the bond between sodium and chlorine forms, how many electrons does sodium have in the resulting outer layer?
What is the charge of a teaspoon of salt (NaCl) crystals? Explain.
An Ionic Bond
Eight
Neutral