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Covalent Bonding Atoms become chemically stable and neutral by sharing electrons (not losing or gaining)
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Covalent Bonding Occurs when atoms share
electrons Different from ionic bonding
Ionic Bond = Atoms completely transfer electrons
Covalent bonding occurs when two (or more) atoms share one or more electrons
Covalent Bonding Covalent bonding occurs when
two or more atoms bond together
The atoms on the right side of the periodic table like to gain electrons These elements will share electrons
in order to fill their valence shells
Covalent Bonding Atoms become chemically stable
and neutral by sharing electrons (not losing or gaining)
Covalent Bonding Covalent bonding is best
illustrated using Dot Diagrams Atomic symbol with the valence
electrons shown You’ve done these before!
Covalent Bonding of Two Hydrogen Atoms
H is in Group One = One valence electron in its outer/only/valence shell
The most electrons in this shell is two electrons
Each H atom will 'want' to pick up a second electron
Covalent Bonding of Two Hydrogen Atoms In order to pick up a second
electron, hydrogen atoms will react with nearby H atoms to form the molecule H2
Covalent Bonding of Two Hydrogen Atoms The H2 is a combination of
equally matched atoms The atoms will share each others
single electron Both atoms have a full valence shell
Covalent Bonding of Two Hydrogen Atoms
The two hydrogen atoms “share” their electrons
Both have “two” valence electrons, so are “happy”
H H
Covalent Bonding Examples Covalent Bonding Chlorine
Covalent Bonding Examples Water (H2O)
is a covalently bonded molecule
Covalent Bonding Examples Covalent Molecule Examples
WATER (H2O) CARBON DIOXIDE (CO2) OXYGEN (O2) METHANE (CH4)
Molecular Compounds There are seven elements that will
form a covalent bond with the same type of atom. H2 F2 Cl2 Br2 I2 N2 O2
Covalent Bonding Multiple Bonds:
Every pair of electrons shared between two atoms is a single covalent bond
Some atoms can share multiple pairs of electrons, forming multiple covalent bonds
For example, oxygen (which has six valence electrons) needs two electrons to complete its valence shell
When two oxygen atoms form the molecule O2, they share two pairs of electrons, forming two covalent bonds
Polarity Non-Polar Covalent Bonds
Bonds where the bonding electrons are shared equally between atoms
No charge
Polarity Polar Covalent Bonds
One atom attracts the electrons more than another resulting in uneven sharing
Slight charge
Steps for covalent bonding problems 1. Write the symbol for each element
in the molecule. 2. Create dot diagrams for each
(helps to use different colors for each element)
3. Rearrange electrons to pair up electrons from each atom.
4. Draw circles to show sharing of electrons
5. Write the chemical formula for the molecule
Molecules vs Compounds
Term Molecule Compound
Definition More than one atom bonded together with covalent bonds.
Atoms of more than one type of element are bonded together (either ionic or covalent bonds)
Examples H20, CH4, CO2, O2 H20, CH4, CO2, NaCl
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