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Chemical Bonding
&
Compounds
Molecule – a particle made up of 2 or more atoms
bonded together
Compound – a substance made up of 2 or more
elements bonded together
Ions - atoms with different numbers of electrons
(makes them electrically charged & opposites attract.)
Chemical bonding occurs when electrons are:
gained, lost, or shared
Formulas tell the type and number of atoms in a
compound. Ex: water - H2O (2 hydrogen, 1 oxygen)
salt - NaCl (1 Sodium , 1 Chlorine)
Compounds have characteristics that differ from the individual
elements. ex: H & O are highly combustible gasses; whereas,
H2O is not. Sodium is highly explosive in water & chlorine is a
green poisonous gas; whereas,
salt is edible and dissolves in water.
Law of Conservation of Matter:
Matter is neither created nor
destroyed, it remains the same
or is rearranged.
Ionic bonds: formed by gaining or losing electrons; then
opposites attract
Characteristics of ionic compounds include:
crystal shape, high melting point, &
high electrical conductivity.
Covalent bonds: formed by sharing electrons
Characteristics of covalent compounds:
low melting & boiling points, and
poor conductors of electricity.
Ionic and covalent bonding animation – YouTube
Covalent molecules can form single bonds
(share 1 pair of electrons), double bonds
(share 2 pairs), or triple bonds (share 3 pairs).
Polar molecules having unequal
sharing of electrons (ex. H2O)
Nonpolar molecules have equal
sharing of electrons. (ex. CO2)
(ex. CO)
Polar molecules melt at
higher temps than nonpolar.
Oxidation number tells how many electrons are
gained, lost, or shared to become stable
All metallic elements, plus Hydrogen & Boron tend to lose
electrons when bonding with nonmetals.
(they have few valence electrons,
so they lose all of their valence electrons)
Nonmetals tend to gain electrons when bonding with metals.
(they have many valence electrons, they will gain
enough to equal 8. example: has 5, gains 3)
Nonmetals tend to share electrons when bonding with
nonmetals.
(ex; covalent bond H2O: 1 + 1 + 6 = 8)
Noble Gases do not form chemical bonds because they
already have a full valence shell (8), so they neither gain,
lose, nor share electrons.
Organic Compounds contain carbon.
Carbon bonds easily because it has 4 electrons
in its outer shell, so it can form 4 separate
covalent bonds.
4 groups of organic compounds in living things
Carbohydrates: –
composed of
C, H, & O in a 1:2:1 ratio.
1.
2. Lipids: (fats) – composed of
long chains of C, H, & O.
3. Proteins – composed of
C, H, O, & N.
4. Nucleic Acids –
composed of
C, H, O, N, & P
Water (H2O ) is an essential compound for all life on
Earth.
Due to its unique structure, water has very good
adhesion_(water sticks to surfaces) and
cohesion (water sticks to water).
This aids in capillary action in plant stems/roots.
Water is often referred to as the universal solvent
because of its ability to dissolve many different
substances. Since water molecules are polar they
attract ions and the charged parts of molecules.
A Wet Towel In Space Is Not Like A Wet Towel On Earth :
Krulwich Wonders... : NPR