Download Week 1 Grade 7 Thursday

Chemistry - Atomic
Structure
Week 1 Grade 7 Thursday
Atomic Structure
Atomic number = number of protons
Atomic number = number of electrons in
a neutral atom (not an ion)
Atomic weight - atomic number =
number of neutrons
Isotopes have different numbers of
neutrons, H normally has 0 neutrons
Neutrons
Protons are all positively charged. If
left alone, they would repel each other.
Neutrons provide additional mass that
is neutral and can keep the nucleus
together.
Hydrogen doesn’t have one because its
one proton can’t repel itself...
Valance
Valance is the number of electrons an
atom will donate or accept during a
reaction
Usually, it is the lower of: the number of
electrons in the outermost shell OR the
number of empty spaces in the
outermost shell.
Valance
Anything with a filled outer shell has a
valance of zero.
Carbon is AMAZING - it has exactly
half of its shell filled (4 out of 8) so it is
incredibly versatile in what it will
accept or donate. No wonder life is
based on it!
Building Atoms, Element
by Element
Start with one of the blank atomic
diagrams.
Add the number of protons, and the
number of neutrons.
Add the electrons into positions on the
shells, innermost shell first.
Building Atoms, Element
by Element
Hydrogen
1
__p
__n
0
Helium
Carbon
2
__p
__n
2
6
__p
__n
6