Download chemistry - billpalmer

CHEMISTRY
Atoms: The Building Blocks of Matter
Southern Boone County HS
William Palmer
CHEMISTRY- Atoms the Building Blocks of Matter
DemocritusGreek
400 B.C.E.
Defined ATOM as
indivisible
CHEMISTRY- Atoms the Building Blocks of Matter
AristotleGreek
Followed
Democritus
Did not believe in
atoms
Set chemistry back
for 2,000 years
CHEMISTRY- Atoms the Building Blocks of Matter
1700s ideal that an
element cannot be
broken down by
ordinary chemical
means.
Questioned if
elements always
combine in the
same ratios form a
compound.
CHEMISTRY- Atoms the Building Blocks of Matter
Chemical Reaction:
Transformation of a
substance or
substances into
one or more new
substances.
CHEMISTRY- Atoms the Building Blocks of Matter
Law of
Conservation of
Mass:
Mass is neither
created nor
destroyed during
ordinary chemical
reactions.
CHEMISTRY- Atoms the Building Blocks of Matter
Law of Definite
Proportions:
A chemical
compound
contains the same
elements in the
same proportions
regardless of the
size or source of
the compound.
CHEMISTRY- Atoms the Building Blocks of Matter
Law of Multiple
Proportions:
If two or more
compounds are
composed of the
same elements,
the ratios of the
masses of the
elements are small
whole numbers.
CHEMISTRY- Atoms the Building Blocks of Matter
Dalton’s Atomic
Theory:
1808 Dalton
English
Theory used to
explain previous
laws
CHEMISTRY- Atoms the Building Blocks of Matter
Dalton’s Atomic Theory:
1) Matter is composed of small particles called
atoms
2) All atoms of the same element are identical;
different atoms are different
3) Atoms cannot be subdivided, created, or
destroyed
4) atoms combine in simple whole number
ratios to form chemical compounds
5) In chemical reactions, atoms are combined,
separated, or rearranged
CHEMISTRY- Atoms the Building Blocks of Matter
Dalton’s Atomic Theory:
Some slight modifications based on nuclear
chemistry and our understanding of atomic
structure.
THE BIG PICTURE
All matter is composed of atoms
Atoms of one element differ in properties from another atom
CHEMISTRY- Atoms the Building Blocks of Matter
STRUCTURE OF THE ATOM
ATOM = The smallest part if an element
that retains the chemical properties of
the element.
Two Regions
Nucleus-small, center of atom
– Protons, positive charge
– Neutrons, neutral charge
Electron Cloud, very large
– Electrons, Negative charge
CHEMISTRY- Atoms the Building Blocks of Matter
SUBATOMIC PARTICLES
PARTICLE
SYMBOL
ELECTRIC
CHARGE
MASS
NUMBER
RELATIVE
MASS
(amu)
ACTUAL MASS
(kg)
ELECTRON
e-
-1
0
.000 5486
9.109x10 -31
PROTON
p+
1
1
1.007 276
1.673x10-27
NEUTRON
n0
1
1
1.008 665
1.675x10-27
CHEMISTRY- Atoms the Building Blocks of Matter
STRUCTURE OF THE ATOM
CHEMISTRY- Atoms the Building Blocks of Matter
COUNTING ATOMS
Atomic Number (Z)
Number of protons in each atom of the
element
Look at Periodic Table for Z
CHEMISTRY- Atoms the Building Blocks of Matter
COUNTING ATOMS
Isotopes
Some atoms have different numbers of
neutrons
Different numbers of neutrons affect weight
of an atom
So, Isotopes of the same element have
different masses (due to the number of
neutrons)
CHEMISTRY- Atoms the Building Blocks of Matter
COUNTING ATOMS
Hydrogen-three isotopes
PROTIUM = 1 proton
DUTERIUM = 1 proton, 1 neutron
TRITIUM = 1 proton, 2 neutrons
All occur in nature, deuterium and tritium
very rare
Tritium is radioactive
CHEMISTRY- Atoms the Building Blocks of Matter
MASS NUMBER
Number of protons and neutrons in the
nucleus of an isotope
Mass number – atomic number = number
of neutrons
Nuclide is a general term for a specific
isotope of an elemet
CHEMISTRY- Atoms the Building Blocks of Matter
CHEMISTRY- Atoms the Building Blocks of Matter
RELATIVE ATOMIC MASS
Based on Carbon -12 atom
1 amu is 1/12 mass of a carbon-12
atom
CHEMISTRY- Atoms the Building Blocks of Matter
AVERAGE ATOMIC MASS
Note that atomic weights on the
Periodic Table are not simple whole
numbers.
This is due to the relative abundance
of each isotope of the element
We will round the atomic mass to
two decimal places for use in our
calculations.
CHEMISTRY- Atoms the Building Blocks of Matter
THE MOLE
A mole (mol) is the amount of a
substance that contains as many
particles as the are in 12 g of carbon12
CHEMISTRY- Atoms the Building Blocks of Matter
AVAGADRO’S NUMBER
The number of particles in exactly one
mole of a pure substance
6.022 1415 x 10 23
or
6.022 x 10 23
IF EVERY PERSON ON EARTH WORKED TO COUNT THE ATOMS IN ONE
MOLE AT THE RATE OF ONE ATOM/SEC, IT WOULD TAKE 3,000,000
YEARS TO COUNT ALL THE ATOMS
CHEMISTRY- Atoms the Building Blocks of Matter
MOLAR MASS
An alternate definition of mole is the
amount of a substance that contains
an Avogadro's number of particles.
1 mol He = 4 g
1 mol Cu = 64 g
The mass of one mole of a pure
substance is called the molar mass
CHEMISTRY- Atoms the Building Blocks of Matter
WRAP-UPS
1. Qs 1-2, page 71
2. Qs 1-4, page 76
3. Qs 1-6, page 87
4. Copy chart on top of 84 onto a card stock
keep for Celebration of Knowledge
5. Qs 7-16, page 89
6. Problems 17-23 page 89-90