1. Unit 4 Compounds, Naming, Formula Writing
Accelerated Chemistry

2. 4.1
Molecule: Smallest unit of a covalently bonded compound.
Molecular Compounds: Compounds composed of nonmetal atoms and formed by the sharing of valence electrons.

3. 4.1 Characteristics of Molecular Compounds Representative Particle
Molecule
Type of Elements
Nonmetals
Physical State
Solid (C12H22O11), Liquid (H2O), Gas (CO2)
Melting Point
Low (Usually Below 300°C)

4. 4.1

5. 4.2
Ions: atoms or groups of atoms that have a positive or negative charge.
Cation: An ion with a positive charge, formed by the loss of electrons, usually metals. Ex. Na+
Anion: An ion with a negative charge, formed by the gain of electrons, usually nonmetals. Ex. Cl-
Ionic Compounds: Compounds composed of metals and nonmetals formed by the transfer of valence electrons.

6. 4.2 Characteristics of Ionic Compounds Representative Particle
Formula Unit
Type of Elements
Metals and Nonmetals
Physical State
Solid (ex. NaCl)
Melting Point
High (Usually Above 300°C)

7. I Bring Clay For Our New House
4.3
Chemical Formula: Shows the kinds and numbers of atoms in a compound
Diatomic Elements: 7 nonmetallic elements exist as diatomic molecules
I Bring Clay For Our New House
I2, Br2, Cl2, F2, O2, N2, H2

8. 4.3
Molecular Formulas: shows the kinds and numbers of atoms present in a molecule of a compound
H2O

9. 4.3
Formula Units: For ionic compounds, the lowest whole number ratio of ions in the compound
NaCl

10. 4.3 The Law of Definite Proportions
In samples of any chemical compound, the masses of the elements are always in the same proportions.

11. 4.3

12. 4.3 The Law of Multiple Proportions
Whenever 2 elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.

13. 4.3

14. 4.4 Li+ Na+ K+ Rb+ Cs+ Be2+ Mg2+ Ca2+ Sr2+ Ba2+ Al3+ Ga3+ N3- P3- As3-
Monatomic ions: ions consisting of only one atom.
Ionic Charges of Representative Elements
Group 1
Group 2
Group 13
Group 14
Group 15
Group 16
Group 17
Group 18
Li+
Na+ K+
Rb+
Cs+
Be2+
Mg2+
Ca2+
Sr2+
Ba2+
Al3+
Ga3+
N3-
P3-
As3-
O2-
S2-
Se2- F-
Cl-
Br- I-

15. 4.4 Many of the transition metals have more than one charge.
You must know the charges and include the charge with Roman numerals in the name.

16. 4.4

17. 4.4 Polyatomic Ions: ions composed of more than one atom.
Know the names, formulas, and charges for 18 of these ions.

18. 4.4