Transcript Ch 1.1 ppt

CHEMICAL INTERACTIONS
Ch 1.1
Atoms are the smallest
forms of elements
ATOMS
• All matter is made of tiny
particles called atoms.
• All atoms have a core called
a nucleus.
• The nucleus contains protons
and neutrons.
PROTONS & NEUTRONS
• Protons are particles with
positive electric charges (+).
• Neutrons are particles with
no electric charges.
• Protons and neutrons have
similar masses and together
make up the mass of an
atom.
ELECTRONS
• An electron has a negative
charge (–) and a very small
mass.
• Electrons move so fast it is
hard to pinpoint their location.
• Not all electrons in an electron
cloud have the same energy.
ELECTRON ENERGY LEVELS
• In atoms, electrons are at fixed
energy levels.
• The 1st energy level is closest to
the nucleus and holds up to 2
electrons.
• The 2nd level holds eight, the 3rd
holds up to 8 or 18.
• Higher levels hold up to 8 or up to
32 or more.
ELECTRON ENERGY LEVELS
Draw correct number of electrons
Example:
MASS OF AN ATOM
• The mass of a proton is
much greater than the
mass of an electron.
• The positive charge of a proton is
equal to the negative charge of an
electron.
• In a neutral atom there are equal
numbers of protons and electrons.
PARTS OF AN ATOM
A
1
E
2
P
N
B
C
3
4
D
PARTS OF AN ATOM
A: NUCLEUS
ENERGY
LEVELS
Up to 8 or
18
Up to 8 or
32
2
8
P
N
B: PROTONS
C: NEUTRONS
D: ELECTRON
CLOUD
Circle your level of
understanding of
these concepts:
1
2 3 4
ELEMENTS
&
CHEMICAL SYMBOLS
ELEMENTS
• Elements are made of only one
type of atom.
• Oxygen, carbon, and hydrogen
are examples of elements.
• Example: Carbon is made of only
carbon atoms.
CHEMICAL SYMBOLS
• The name of an element can be
represented by a chemical
symbol.
• When one letter is used as a
symbol it is a capital letter.
• Example: oxygen is O,
hydrogen is H, & carbon is C. .
.
• When a symbol contains two
st
letters, the 1 letter is a capital
nd
and the 2 is in lower case.
• Example: helium is He,
chlorine is Cl, & lithium is Li.
•Most symbols come from the
English name of the element;
some come from the Latin name.
•The symbol is the one or two letter
abbreviation for the element.
K * Potassium
O * Oxygen
Cl * Chlorine
S
*
Sulfur
Na * Sodium
The element name is the chemical
name given to a substance.
•
SYMBOL BOX
Atomic number
2
Symbol
Element name
Atomic mass
He
Helium
4.00
SYMBOL BOX
SYMBOL BOX
• Atomic number: the number of
protons in an atom found in the
nucleus.
• Helium has two protons, so its atomic
number is 2.
• Atomic mass: the average number of
protons and neutrons in an atom.
This is the relative mass of the element
compared to carbon as a standard.
•Mass number: total number of
protons and neutrons in an atom.
Atomic Number = # of Protons = # of Electrons
ATOMIC MASS (AVERAGE- DECIMAL)
MASS NUMBER (WHOLE NUMBER)
= # of Protons + # of Neutrons
OR = # of Electrons + # of Neutrons
OR = Atomic Number + # of Neutrons
Subtracting the # of protons (atomic # or # of
electrons) from the mass number, will give
you the # of neutrons.
PERIODIC TABLE
By the middle of the 19th century, a
number of elements had been discovered.
• Dmitri Mendeleev, a Russian scientist,
arranged the elements into the Periodic
Table.
• Certain chemical properties were
repeated regularly.
• These properties were related to the
sum of the protons and neutrons in an
atom.
Mendeleev’s table contained the 65
elements then known and blank spots
where he predicted the properties of
elements not yet discovered.
Some problems occurred with his
arrangement. As a result, today’s
classification system is based on the
atomic numbers of elements.
This organization of elements is called the
PERIODIC TABLE.
PERIODIC TABLE
• Scientists have
discovered 118 substances
called elements.
• 92 of these occur naturally, the
rest are made in laboratories.
• An element is a substance that
cannot be broken into smaller
substances.
ISOTOPES
• Atoms of the same element
ALWAYS have the same number
of protons.
• All atoms of the same element
do NOT always have the same
number of neutrons.
• Isotopes: atoms of the same
element with different numbers
of neutrons.
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METALS
H hydrogen
Na sodium
Mg magnesium
K potassium
Ca calcium
Ba barium
Fe iron
Zn zinc
Ag silver
Cu copper
• Mn manganese
• Li lithium
• Pb lead
• Ni nickel
• Co cobalt
• Au gold
• Al aluminum
• Sn tin
• Hg mercury
NON-METALS
• Cl
•F
• Br
•O
•S
•I
•N
•P
chlorine
fluorine
bromine
oxygen
sulfur
iodine
nitrogen
phosphorus
• He
•B
• Si
• Ne
• Rn
•C
• Xe
• Ar
helium
boron
silicon
neon
radon
carbon
xenon
argon