Post on 23-Dec-2015
Warm-Up #27 A. 40
1. Ionic bonds form between a metal and another metal. T / F
2. A bond between two nonmetals is called a covalent bond. T / F
3. Ionic compounds have a low melting point. T / F
4. Draw the Lewis dot structure for F.
5. Draw the Lewis dot structure for Li.
Warm-UP #29 Copy and Answer
1. Group 1 has two valence electrons. T / F
2. Group 13 has thirteen valence electrons. T / F
3. Group 18 has 8 valence electrons. T / F
4. What is the Lewis dot structure for Be?
5. What is the Lewis dot structure for P?
Remember…
• Ionic bonds forms between metals and nonmetals.
• An ionic bond happens when one atom transfers its valence electron(s) to another atom.
Covalent Bonding
• What are covalent bonds?– A covalent bond forms when atoms share one or
more pairs of valence electrons.– Covalent bonds form between a nonmetal and
another nonmetal.
How to Represent Covalent Bonds
• Let’s consider H2, the simplest molecule.
• What is the Lewis dot structure for Hydrogen?
• Use the Lewis dot structure to show two Hydrogen atoms combining.
H•
hydrogen atom
H•
hydrogen atom
+ •H
hydrogen atom
H•
hydrogen atom
+ •H
hydrogen atom
H H
hydrogen molecule
•
•
Shared pair of electrons
How to Represent Covalent Bonds Cont.
• What would the product of the two Hydrogen atoms look like?
• Use Lewis dot structures to show the entire reaction
H H
hydrogen molecule
•
•
• • F•
• ••
atom
• • •
• • F • •
atom
•+ F F ••
•
•
••
• • • •
• • • •molecule
or••
structural formula
••
• • • •
• • • •F - F
shared pair
Covalent Bonding
• Show the reaction of two Fluorine atoms combining to create F2.
Can atoms share more than one pair of electrons?
• YES!!!• Atoms sometimes share more than one pair of
electrons to attain 8 electrons.• Double covalent bonds involve two shared pairs
of electrons.
Covalent Compounds
• Most items around you are covalently bonded such as water, sugar, oxygen and cellulose in wood– What are some other covalently bonded
things?
• Properties of Covalent Compounds– Brittle Solids– Low melting and boiling points