1. Chapter 6 Chemical Names and Formulas

2. Molecules and Molecular Compounds
Molecule - Basic unit of a compound
Molecular Compound - a compound that is composed of molecules (two or more nonmetals)

3. Characteristics of Molecular Compounds
Representative unit- molecule
Type of elements- nonmetals ONLY
Physical state- solid, liquid or gas
Melting point- low

4. Ions and Ionic Compounds
Ion- atoms or groups of atoms with a charge.
Ions form when an atom or group of atoms gain or lose electrons

5. Atom vs. Ion Atom – neutral particle # protons = # electrons
Ion – charged particle
(lost or gained electrons)
# protons ≠ # electrons
What if...
Note:
can never
lose or gain
protons!

6. 3 – 3 = 0 This is an ATOM Charge = # of protons – # of electrons
Find the charge…
3 – 3 = 0
neutral
This is an ATOM

7. protons > electrons = + charge
lost 1 electron
Sodium atom
Sodium ion
Protons: 11
Electrons: 11
Charge: 0
Protons: 11
Electrons: 10
Charge: +1
protons > electrons = + charge

8. protons < electrons = – charge
gained 1 electron
Chlorine atom
Chlorine ion
Protons: 17
Electrons: 17
Charge: 0
Protons: 17
Electrons: 18
Charge: -1
protons < electrons = – charge

9. Ions and Ionic Compounds
1. Cation - a positive ion formed when an atom loses electrons.
A positive ion would have the same name as a normal atom
BUT… they have the same name, they have different chemical properties
Example- Na and Na+
Sodium Atom Sodium Ion

10. Ions and Ionic Compounds
2. Anion- a negative ion formed when an atom gains electrons.
The name of an anion is changed to -ide
Example: Cl and Cl-
chlorine atom chloride ion

11. Characteristics of Ionic Compounds
Ionic compound- composed of metals and nonmetals (cations and anions)
Ionic compounds are electrically neutral
The charges on the anions and cations in the compound equal zero
Representative Unit - formula unit
Type of elements – metals and nonmetals
Physical State - solids
Melting Point - high

12. Representing Chemical Compounds
Chemical Formula - shows the kinds and numbers of atoms in the smallest representative unit of a substance
Examples: O2, N2
Molecular Formula - shows the kinds and numbers of atoms in a molecule of a compound. (groups of nonmetals…molecular compounds)
Examples: CO2, H2O
Formula Unit - lowest whole-number ratio of ions in an ionic compound. (metals and nonmetals…ionic compounds)
Examples: MgCl2, AlCl3

13. Is the compound ionic or molecular?
NaCl
N2O
SO2
MgCl2
CCl2

14. Name each: atom or ion Mg Li
Mg+2
Li+1 Cl Br
Cl-1
Br-1

15. Ionic Charges: +1 +2 +3
+/-4 -3 -2 -1
skip a few
Charge
Varies

16. Ionic Charges
Transition Metals- can have more than one charge, a Roman numeral in parenthesis indicates the numerical value of the charge

17. Ionic Charges Exceptions Ag is always +1
cadmium and zinc are always +2
Practice: What is the charge of each ion typically formed by each element?
Sulfur
Lead, 4 electrons lost
Strontium
Argon
Bromine
Copper, one electron lost

18. COMPOUNDS

19. Writing the formulas of an ionic compound
IONIC COMPOUNDS
Writing the formulas of an ionic compound
Need to look at the charges of both ions because the compound must be neutral. (overall charge = 0)
Find the
charges of the
following
elements - -1 Na +1 Ca +2 Br -3 +3 P -2 O Al

20. Na O Al S Na2O Al2S3 Crisscross the numbers and drop the charges +1 -2+3 -2 Na O Al S 2 2 3
Na2O
Al2S3

21. ( ) Mg ( ) Ca NO3 PO4 Ca(NO3)2 Mg3(PO4)2
Use parenthesis if you have more than one polyatomic ion (an ion with more than one atom) +2 -1 -3
( ) Mg +2
( ) Ca
NO3
PO4 3 2 2
Ca(NO3)2
Mg3(PO4)2

22. Mg ( ) O Sn CO3 MgO Sn(CO3)2 Reduce the subscripts if possible -2 -2+2 +4
( ) O Sn
CO3 2 2 2 4 2
MgO
Sn(CO3)2

23. Al3+ SO42-
According to the information above, what is the chemical formula for aluminum sulfate?
AlSO4
Al2(SO4)3
Al3(SO4)2
Al6SO4

24. What type of bond is formed. between two potassium atoms and
What type of bond is formed between two potassium atoms and one sulfur atom?
Ionic Bond
Metallic Bond
Hydrogen Bond
Covalent Bond