Transcript Chemistry: The Basics

Chemistry
Why do you think we have to
learn about Chemistry in a
Biology class?
Um, whoAtomic Theory
I’m Oxygen.
is this?
It
sure
is
1. All
composed of tiny
I amdivisible
different
Heelements
looks
nice
particles
from you, but
pretty called atoms.
hanging
Tell
mefunctional
I’m sure
we
different
Atoms
are
the
basic
unit
of
out with
about it,
could find
from you
matter.
you,
Carbon!
some way to
and me,
Carbon.
bond!
Carbon.
1. Atoms of the same element are identical
Still more of Atomic Theory…
3. Atoms of different elements can
physically mix together or can chemically
combine to form compounds.
4. Chemical reactions occur when:
– atoms are separated, joined or rearranged;
– however, they are never changed into atoms
of another element.
The three kinds of subatomic
particles
1. Protons (p+)
– 1 AMU (Atomic Mass
Unit)
– One unit of positive
charge
2. Neutrons (n0)
– 1 AMU (Atomic Mass
Unit)
– No charge or neutral
The three kinds of subatomic
particles
3. Electrons (e-)
– Mass of electron is so small it is not even
calculated into atomic mass
– One unit of negative charge
Atomic Structure
Protons and Neutrons make up the nucleus
Electrons spin around in orbitals surrounding
the nucleus
What is an orbital?
Outer orbitals =
Max out at 8
Innermost Orbital =
Maxes out at 2
What makes atoms different from
each other, if they have the same
basic parts?
The Atomic Number
Definition: The number of
protons in the nucleus of
an atom of that element.
Why protons?
Why not neutrons?
Or electrons?
• Oxygen’s Atomic Number is 8.
– How many protons does it have? _______
8
8
– How many neutrons does it have? ________
8
– How many electrons does it have? ________
• Wait a minute, how do we know we have
that many of each atomic component?
Atomic Mass (AMU)
• The total number of protons and
neutrons is called the atomic
mass.
Based on this nucleus, what
is the atomic mass? 4
+ +
What element is it? Helium
What about those special cases?
• Sometimes there are more or less
neutrons in a nucleus, these are called
isotopes.
The Atomic
Number
Element’s
Name
Atomic Mass
5
5
P = _____
B
6
N = _____
Boron
10.81
5
E = _____
Bohr Diagram
Lewis
Structure
B
were
HiYou
there!
Greetings, Nitrogen.
Bonding
and Chemical
right!
I am
We
are Hydrogen
I’mReactions
now
Ammonia!
atoms. Perhaps we
Nitrogen.
But, am I an
•willChemical
Bonding:
change the
way
Am
I
an
atom or a
you
think
about
Combining Atoms of Elements
to
form
atom
or
a
compound
yourself.
Chemical Compoundscompound?
now?
Oh, you can’t be
serious!
Bonding
To achieve stability, an atom will
either gain, lose or share electrons.
Ionic Bonds:
A bond that involves a transfer of electrons
Ionic Bonds
Sodium Chloride = Salt!Chloride
Chlorine
Ion (+1)
Ion (-1)
Can you guess which
Covalent Bonds
element I am?
What
will
complete
my
• A covalent bond is a chemical bond
valence shell?
formed by sharing electrons.
Different types of Covalent Bonds
Single Bond: One pair of shared electrons
Double Bond: Two pairs
= of
H shared
– H electrons
Triple Bond: Three pairs of shared electrons
O=C=O
C
Lone
pairs: Cyanide
Electron (HCN)
pairs not
shared
Hydrogen
can
form this.
between
Can
you? atoms
H
N
H
H
Bonding Basics Practice
1-
Ionic Bonds
1. Mg + Br
2+
Br
2. Pb + S
1-
Mg
2-
4+
S
Pb
Br
MgBr2
2-
S
PbS2
1-
Cl
3. Al + Cl
Cl
Al
Cl
1-
3+
1-
AlCl3
Bonding Basics Practice
Covalent Bonds
1. H + Cl
Cl H – Cl
H
Cl
2. C + Cl
Cl
C
Cl
Cl
O
Si
Cl
C
Cl CCl4
Cl
Cl
3. Si + O
HCl
O
O = Si = O
SiO2
Bond with your classmate!
• Each of you will have an element.
• The charge – or oxidation number – is on
the element.
• Your goal is to bond with as many of your
classmates as possible.
• Balance your equations!
– i.e., Magnesium (Mg) and Bromine (Br) must
make… MgBr2
Bond!