Unit C: Atoms, elements, and Compounds
7.3: How Atoms Combine
pg. 263
Key Concepts:
1. Elements can combine to form compounds.
2. Metals and non-metals combine to form ionic compounds. Non-metals combine to
form molecules.
- Atoms bond together they form stable compounds.
- Noble gases are stable elements, they have a complete octet. Their outer electron shell is
completely full (8).
- Other elements on the periodic table do not have complete octets; therefore they are not
stable and will react.
- Bonds between atoms are created when, an atom loses an electron, an atom gains an
electron, or atoms share electrons.
Metals and Metals
- Alloys are mixtures of two or more metals. Alloys are not compounds, they are solid
solutions.
- Compounds are created when bonds are formed between two or more atoms, in fixed
ratios.
Metals and Non-metals
- Ionic compounds are formed when atoms lose or gain electrons. Oppositely charged
atoms are attracted to each other and form bonds, ionic compounds.
- An atoms that loses an electron become positively charged, Anion.
- An atom the gains an electron becomes negatively charged, Cation.
- A bond is formed between an anion and a cation.
- Ionic compounds are given chemical names and common names. When naming and
ionic common the first name is the metal element, and the second name is the non-metal
element, but the name is slightly changed. The ending is changed; the ine is changed to
ide.
Ex. Chlorine is changed to chloride
- Na+ is combined with Cl- to form the ionic compound NaCl.
- Its chemical name is Sodium chloride.
Figure 2: a) Ions of opposite charges attract each other to form layer after layer of
closely packed ions.
Table 1: Ionic Compounds
Chemical Formula
Chemical Name
Sodium chloride
NaCl
KCl
CaO
NaOH
CaCO2
NaHCO3
Mg(OH)2
CuSO4
Potassium chloride
Calcium oxide
Sodium hydroxide
Calcium carbonate
Sodium hydrogen
carbonate
Magnesium
hydroxide
Copper (II) sulfate
Common Name
Salt
Potash
Quicklime
Lye
Limestone, chalk
Baking soda
Milk of magnesia
Bluestone
Common Use
Food seasoning,
melting road ice
fertilizer
masonry
Drain cleaner
Building materials
Rising agent in
baking
antacid
Algicide and
fungicide
Non-metals and Non-metals
Covalent Bond: a bond formed when two on-metal atoms share electrons.
- Non-metals can combine with other non-metals but hey do not form ionic compounds.
- Non-metals do not lose an electron or gain an electron when forming a bond with other
non-metals.
- Non-metals will share electrons to create a completely octet for both elements.
- These types of bonds are called covalent bonds, and they form molecular compounds.
- When hydrogen and oxygen interact they will form covalent bonds and create water.
- Hydrogen and oxygen will share electrons to make a complete octet for both atoms.
ex. O2 and H2 combined to create H20.
Figure 3: A covalent bond results from the sharing of electrons. In the hydrogen
molecule (H2), the two hydrogen nuclei simultaneously attract both electrons. The
notation H-H can also be used to represent a hydrogen molecule. The dash between the
bonding elements represents the covalent bond.
Table 2: Common Molecules
Chemical formula
Chemical Name
Common Name
Nitrogen
Oxygen
Trioxygen
Nitrogen
Oxygen
Ozone
H2 O
Dihydrogen oxide
Water
CO2
Carbon dioxide
Dry ice (solid)
HCl
Hydrogen chloride
Muriatic acid
(solution)
CH4
NH3
Methane
Nitrogen
trihydroxide
Natural gas
Ammonia
C3H8
C2H4O2
Propane
Acetic acid
Propane
Vinegar
C9H8O4
Acetylsalicylic acid
(ASA)
Aspirin
N2
O2
O3
Common
use/Source
Approx. 80% of Air
Approx. 21% of Air
In the stratosphere
absorbs ultraviolet
light
Needed in all cells
home for aquatic
organisms
Carbonated
berverages,
refrigeration
Stomach acid,
important industrial
chemical
fuel
Used in fertilizers
and household
cleaners
fuel
Used in cooking,
preservatives
Blood thinner, for
pain
Check Your Learning
Questions 1 – 10, page 266
Summary:
- Metals do not form compounds with other metals. They form solutions called alloys.
- Metals and non-metals combine by forming charged particles called ions. Oppositely
charged ions attract and form ionic compounds.
- Table salt, or sodium chloride (NaCl), is an ionic compound.
- Non-metals share electrons with other non-metals to make molecules.
- The atoms in a molecule are held together by covalent bonds.
- An example of a molecule is water (H2O). Each water molecule consists of two
hydrogen atoms and one oxygen atom covalently bonded to each other.
- Many chemicals have both chemical names and names that are used in common
language.
Table 1: Ionic Compounds
Chemical Formula
NaCl
Chemical Name
Sodium chloride
Common Name
Salt
KCl
CaO
NaOH
CaCO2
NaHCO3
Potassium chloride
Calcium oxide
Sodium hydroxide
Calcium carbonate
Sodium hydrogen
carbonate
Magnesium
hydroxide
Copper (II) sulfate
Potash
Quicklime
Lye
Limestone, chalk
Baking soda
Mg(OH)2
Milk of magnesia
Common Use
Food seasoning,
melting road ice
fertilizer
masonry
Drain cleaner
Building materials
Rising agent in
baking
antacid
Bluestone
Algicide and
fungicide
Chemical Name
Common Name
Nitrogen
Oxygen
Trioxygen
Nitrogen
Oxygen
Ozone
H2 O
Dihydrogen oxide
Water
CO2
Carbon dioxide
Dry ice (solid)
HCl
Hydrogen chloride
Muriatic acid
(solution)
CH4
NH3
Methane
Nitrogen
trihydroxide
Natural gas
Ammonia
C3H8
C2H4O2
Propane
Acetic acid
Propane
Vinegar
C9H8O4
Acetylsalicylic acid
(ASA)
Aspirin
Common
use/Source
Approx. 80% of Air
Approx. 21% of Air
In the stratosphere
absorbs ultraviolet
light
Needed in all cells
home for aquatic
organisms
Carbonated
berverages,
refrigeration
Stomach acid,
important industrial
chemical
fuel
Used in fertilizers
and household
cleaners
fuel
Used in cooking,
preservatives
Blood thinner, for
pain
CuSO4
Table 2: Common Molecules
Chemical formula
N2
O2
O3