Transcript A1.1 The Structure of Matter

Do Now
1. Get out your homework:
• Page 8 practice # 1
• Page 9 practice #5
• Page 10 practice #6
2. Check page 10 practice #6
Look at the back of the textbook.
Answers
Page 8 practice # 1
#1
a) Protons are found in the nucleus and have a positive
charge. The # of protons is the same as the atomic
number.
b) Neutrons are found inside the nucleus and have no
charge. They add mass to the atom.
c) Electrons are found surrounding the nucleus and have
a negative charge. They play a role in bonding.
Answers
a) Carbon
b) Hydrogen
c) Aluminium
Pg. 9 # 5
Answers
d) lithium
e) sodium
f) fluorine
Pg. 9 # 5
Answers
Pg. 9 # 5
g) neon
h) helium
Pg. 10 #6 is in the back of the textbook
A1.1 The Structure of Matter
The Plan
• Go over pg. 5 & 6 of work booklet.
• Review valence electrons, Bohr & Lewis dot
diagrams.
• A1.2 Atomic bonding and properties
• Work on summative assignment.
A1.2 Atomic Bonding &
Properties
Science 20
Unit A
Review-Valence Electrons
• An electron that occupies the outermost energy level in an atom.
• It is these electrons that determine the chemical properties of an
atom.
• Atoms of different elements that have similar electron
arrangements have similar characteristics and are arranged in
families.
• All atoms strive to complete the outer shell with electrons and
thus become a stable atom. They can complete these outer shells
by gaining, losing or sharing electrons from other atoms.
Metals vs. Non-Metals
• Metals tend to form
positively-charged ions
(cations)
• Non-metals tend to
form negatively-charged
ions (anions)
Aluminum
• Is a metal that has luster, good
heat and electrical conductivity,
is malleable and ductile and
tends to form positive ions.
• A non-metal is not flexible, does
not conduct well and tends to
form negative ions.
Rock Salt
• Is a compound which is
made up of elements
(sodium & chlorine).
• If one element is a metal &
the other is a non-metal
then the compound is called
an ionic compound and
the bond between a positive
& a negative ion is called an
ionic bond.
Ionic Bonds
• Metals + Non-Metals = ionic bonds
Sharing Electrons
• Two or more non-metallic atoms tend to
share electrons to complete the outer shell.
• By sharing they form covalent bonds.
Plastics
• Composed of hydrogen & carbon,
which are both non-metals.
• If two non-metals combine they form
molecular compounds.
The bonding does not involve ions,
rather a sharing of electrons and the
bond is called a covalent bond.
• The resulting compound is called a
molecule.
Covalent Bonds
• Nonmetal + Nonmetal = covalent bonds
In General
• Bonds formed by molecular compounds are
weaker than ionic compounds.
• The properties of the categories of matter, on pg.
21 of your text, can explain:
– Why molecular compounds will melt quicker than
ionic compounds
– Why ionic crystals will snap if you try bending them,
while molecular compounds will bend
– Why metals conduct better
– Why molecular compounds can dissolve
Assignment
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Practice problems #2, 3, & 9 (p. 14)
Read pgs. 15-23
Practice Problems #9-12 (p. 17-23)
1.2 Questions: Pg. 23-24 #1-5
Diagrams of Atoms Summative Assignment–
Due Monday, February 8th.