Chemical Bonds
Section 2 - Types of Bonds
Ionic Bonding
To reach a stable energy level, atoms lose or
gain electrons.
An atom is neutral but will become a charged
atom if there is a transfer of electrons
When an atom loses or gains an electron, it
becomes an ion.
Ion – charged (atom) particle that has either
fewer or more electrons than it has protons
Ionic Bonding
Negative ion – has more electrons than
protons
Positive ion- has more protons than
electrons
Ionic Bond
bonding that involves a transfer of
electrons
forms when ions attract each other and
form a compound
force of attraction between a positive ion
and a negative ion
Electron-dot Diagram
drawing that uses the chemical symbol for
an element surrounded by a series of dots
to show the electron bonding taking place.
The dots represent the valence electrons
also called Lewis Dot Structure/diagram
Covalent Bonding
A lot of energy is required for an atom to
lose or gain electrons
Example: elements in Group 14 have four
electrons in their outermost level – it is
easier for these elements to become
stable by sharing electrons
Covalent Bonding
bonding in which electrons are shared
rather than transferred
The attraction between electrons and the
positively charged nucleus of the atoms
hold the atoms together
Molecule
A group of two or more atoms joined
together by a formed by a chemical bond
Unequal electron sharing
Electrons are not always shared equally
the nucleus of some atoms will attract
electrons more strongly and electrons will
stay closer to that atom’s nucleus
Nonpolar and Polar molecules
When two atoms that are exactly alike form a
covalent bond, they share the bonding electrons
equally.
Nonpolar molecule, the electrons are shared
equally in the bond
When one atom’s nucleus has a stronger force,
electrons will stay closer to that atom.
Example:
Water molecule H2O
Water Molecule (cont)
The oxygen atom forms a covalent bond
with each hydrogen atom
The oxygen atom has a stronger
attraction for the bonding electrons – the
electrons spend more time closer to the
oxygen atom.
This gives the oxygen atom a partial
negative charge and the hydrogen a
partial positive charge
Water Molecule (cont.)
Because the water molecule has an end
that is partially positive and an end that is
partially negative, water is a polar
molecule.
Polar means “having oppositely charged
ends”
**This polarity helps give water the
structure to support life (cell systems)