8th Grade-Ch. 1 Sec. 4 Covalent Bonds
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Transcript of 8th Grade-Ch. 1 Sec. 4 Covalent Bonds
Ch. 1 Sec. 4
ss
covalent bonds
• usually form between 2 nonmetals
C2H6
molecule •neutral group of atoms joined by covalent bonds
CH4
Carbon has 4 electrons in its outer shell. It needs 4 more electrons.
Hydrogen needs 1.
Nonpolar bond• covalent bond in which valence
electrons are shared equally
• ex: oil
Polar bond
Covalent bond in which electrons are shared unequally
Water molecules are polar
Polar bond
Polar bond
Unequal sharing of electrons
Polar bond
• Unequal sharing of an electron in a polar-covalent bond between 2 atoms is like 2 neighbors buying and sharing one snowblower.
• But one neighbor has a much
longer driveway than the other. • After a snowstorm, the snowblower will
spend much more of its time at the house with the longer driveway than the other.
• F, O, Cl have long driveways.
Be Nice, Clear Your IceBe Nice, Clear Your Ice
Fluorine forms a nonpolar bond with
another fluorine atom.
In hydrogen fluoride, fluorine attracts
electrons more strongly than hydrogen does, so the bond formed is
polar.
DOUBLE BOND
• 2 pairs of electrons are shared
TRIPLE BOND
• 3 pairs of electrons are shared
molecular compound
• molecules having covalently bonded atoms
H2O
Properties of molecular compounds
CH3CH2OH
1. Lower point
& boiling point
2. Poor conductors of electricity
Click here for Ionic and Covalent Bonding Quiz
YouTube video-Ionic and Covalent Bonding
Review Time
What holds covalently bonded atoms together?
• The force that holds atoms together in a covalent bond is the attraction of each atom’s nucleus for the shared pair of electrons.
How does unequal sharing of electrons occur, and how does it affect molecules?
• Atoms of some elements pull more strongly on shared electrons than do atoms of other elements. As a result, the electrons are pulled more toward one atom, causing the bonded atoms to have slight electrical charges.
What are the properties of molecular compounds?
• Molecular compounds generally have lower melting points and boiling points, and they do not conduct electricity when dissolved in water.