Transcript Chapter 2 Lecture

Chapter 2 Topics:
Elements and the Periodic Table
http://www.youtube.com/watch?v=1PSzSTilu_s
Can you find the halogens? Alkali metals? Noble gases? Transition
metals? Alkaline earth metals? Lanthanides and actinides? Metals?
Nonmetals? Semimetals or metalloids?
Balancing Equations
http://www.youtube.com/user/MarkRosengarten#p/c/65159266CFC74682/18/
What
coefficients balance this equation:
QjVYz00-Kxc
Mg + Al2S3 → Al + MgS
Types of Reactions
http://www.youtube.com/user/MarkRosengarten#p/c/65159266CFC74682/19/dxlWtsFinTM
Classify the reaction type above.
Subatomic Particles!
Particle
Charge
Mass
Location
Electron
-1
1/1800
Outside the
nucleus
Proton
+1
1
Inside the
nucleus
Neutron
0
1 + 1/1800
Inside the
nucleus
Vocabulary, vocabulary, vocabulary
The number on the
Periodic table is the
ATOMIC WEIGHT.
This is an average
mass of all the
ISOTOPES that
occur in nature.
Atomic mass or mass number is a
WHOLE
number that must be rounded from
the
number on the periodic table. It is
the
number of protons + the number of
neutrons
in an atom of the element.
Isotopes are atoms of the same element that have
different MASSES. They have the same number
of PROTONS, but different numbers of NEUTRONS.
Isotope
Notation!
Isotopes of an
element have
the same physical
and chemical
properties. They
only have different
MASSES!
40
20Ca
How many protons? What is the atomic
number? What is the mass number? How many
neutrons? How many electrons? (Hint: All atoms
must be neutral!)
21Ne
How many protons? How many neutrons?
How many electrons?
19
9X
How many protons? How many neutrons?
What element is this?
An isotope of an element has 3 protons and
4 neutrons. Write its isotope notation.
Lithium exists as two isotopes: lithium-7 and lithium-6
Lithium-7 has a mass of 7.015 amu and makes up
92.58% of lithium
Lithium-6 has a mass of 6.015 amu and makes up
7.42%
What is the atomic weight of lithium (on the
periodic table)? Which isotope is more abundant,
lithium-6 or lithium-7?
To calculate the average atomic mass of lithium,
multiply the mass of each isotope by its
abundance, then add these 2 values to each other
Mass Defect
There's actually one more reason
why the mass isn't a whole number....
recall that the mass of a neutron isn't
exactly 1 amu. And when protons
and neutrons stick together
to make a nucleus, a small
amount of mass is
converted to energy, making
a very strong bond called
strong nuclear force.
E=mc2
When an
atom loses
electrons it
becomes a
positively
charged
ion called a
cation.
Atoms are neutral
because they have
the same number of
protons and electrons.
When an
atom gains
electrons it
becomes a
negatively
charged
ion called
an anion.
39K+
How many protons does this isotope have?
How many neutrons?
How many electrons does this ion have?
16O2-
How many protons does this isotope have?
How many neutrons?
How many electrons does this ion have?
And now, I am excited to present to
you...
MOLES!!!
http://www.youtube.com/watch?v=1R7NiIum2TI
23
10
1 mole = 6.02 x
atoms =
the atomic weight in grams
There are 6 conversion factors that
can be made from these equalities.
Can you write them all?