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10/16/2014
• Take our your worksheet from yesterday!
• Complete your WS on determining the
identity of an element before your Bell
Ringer.
• If you get finished, copy the Bell Ringer
into your journal and answer the questions.
• TEST tomorrow so look over your notes
NOW.
Thursday 10/16/2014 Bell Ringer:
Write and complete the statements.
1. The identity of an element is
determined by _______________.
2. In a neutral atom, the # of protons
equals the # of ____________.
3. The # of neutrons can change.
Neutrons add ________ to the atom.
Thursday 10/16/2014 Bell Ringer:
Write and complete the statements.
1. The identity of an element is
determined by # of protons in the
nucleus. A=P
2. In a neutral atom, the # of protons
equals the # of electrons. A=P=E
3. The # of neutrons can change.
Neutrons add mass to the atom.
Elements are made of only 1 kind of atom, and the
atom is identified by the # of protons in the nucleus.
Mass
• Mass is the amount of matter in something.
• The unit of measure for atoms is amu
(atomic mass unit)
Atomic Mass Unit
1 atomic mass unit = 1.66053886 ×
10-27 kg
Kg is Kilograms
Relative Mass of Subatomic
Particles
What is a Symbol?
Elements and Chemical Symbols
Chemical Symbols / Element Names
Co
Cobalt
C
Carbon
Writing Chemical Symbols
1. First letter is capitalized
2. Second letter is lower case
3. NO period at the end
H Cl O Hg Fe Sn C He
Does it really matter?
Co or CO
Co
Cobalt-60, extensively used as a tracer and a
radiotherapeutic
http://members.tripod.com/duebills/27.html
Co
Alloys for metals used
in jet turbines
CO
Kills 200 People
in United
States
http://www.cpsc.gov/cpscpub/pubs/466.html
CO
Produced by Incomplete
Burning of Fossil Fuels
CO
carbon
oxygen
carbon monoxide
Colorless
Odorless
Poisonous gas
Think before
you write a
Element’s
Symbol
Elements are substances:
•That cannot be broken down
into other substances
•Made of atoms with the same
number of protons in the nucleus
Elements are listed on the
Period Table
Use your copy of the
Periodic Table of Element
Correctly write the symbol for:
1.Carbon
2.Nitrogen
3.Oxygen
4.Iron
5.Chlorine
C
N
O
Fe
Cl
Atomic Number
Number of Protons in every
Atom of that Element
What is the name of the
element with the following
number of protons?
A.2 Helium
B.6 Carbon
C.8 Oxygen
D.11 Sodium
E.47 Silver
Protons
+ electrical charge
+
Neutron
No electrical charge
Electrons
- electrical charge
-
Neutral Atoms
(Atoms without Electric Charge)
Have equal numbers of:
Protons (+ charges)
Electrons (- charges)
A=P=E
• Atomic # = # Protons = # Electrons
• Because the number of positive
charges equals the number of negative
charges, the atom is neutral (no charge)
How many electrons?
1 proton
1 electron
9 protons
9 electrons
99 protons
99 electrons
Atomic Mass
The atomic mass is listed on the individual
element card on the Periodic Table.
Isotopes
• Not all atoms of the same element have the same number of neutrons.
Most Carbon atoms have 6 neutrons, although some have more and
some have less. Atoms of the same element with differing numbers of
neutrons are called isotopes. The number of neutrons does not change
the atom or the element it makes up; it just changes the mass of the
atom. Most elements have isotopes.
Atomic Mass Number
Protons + Neutrons
To calculate # of neutrons
1. Round the Mass Number
to the nearest whole
number
Round to 28
Atomic Mass Number
Protons + Neutrons
Calculate # of neutrons
2. Subtract Atomic Number
From Mass Number
28 (Mass #)
-14 (Atomic #)
14 Neutrons
To find the AVERAGE # of
Neutrons in the atom
• Round the atomic mass to a whole #
• Subtract the # of protons (also the atomic #)
• The difference is the average # of neutrons
in the nucleus.
M–A=N
M is the Mass # (atomic mass)
A is the atomic # (# of protons)
N is the # of neutrons
Use the Periodic Table
and Math Skills
to fill in the blanks
Symbol
Atomic
#
Mass
#
He
2
4
3
7
N
#
Protons
#
Neutrons
#
Electrons
2
3
7
7
# protons is the atomic #
protons + neutrons = mass #
#electrons = # protons
Symbol
Atomic
#
Mass
#
#
Protons
#
Neutrons
#
Electrons
He
2
4
2
2
2
Li
3
7
3
4
3
N
7
14
7
7
7
•Part 2
Compounds
2 or More Elements
Chemically Combined
Hydrogen
2-H: 1-O
Hydrogen
Oxygen
Ratio
2:1
H
H
O
H2O
1 is not
shown
Formulas use element symbols
with subscript numbers
Water
Change the ratio
Change the substance
Hydrogen 2:2
Peroxide H2O2
Subscript numbers
http://www.wonderquest.com/images/2003-08-08-peroxide.jpg
No subscripts??
1Na
NaCl
Salt
1Cl
How many elements? 2
Sugar
C6H12O6
How many elements? 3
How many hydrogen atoms? 12
√ Check your
understanding
1. The symbol for carbon is –
A Ca
B
c
C
CA
D C
1. The symbol for carbon is –
A Ca Incorrect:
Symbol for calcium
B
c
Incorrect:
st
1 letter is always a
capital
1. The symbol for carbon is –
C
CA
D C
Incorrect:
C is carbon
There is no element
with the symbol A
Correct:
Capital C is the
symbol for carbon
2. How many protons are in
an atom of sodium?
A 11
B
12
C
23
D 34
2. How many protons are in
an atom of sodium?
A 11
Correct:
atomic # is 11
B
12 Incorrect:
12 is the number of
neutrons
2. How many protons are in
an atom of sodium?
C
23 Incorrect:
23 is the mass number
D
Incorrect:
34
No subatomic particle #
is found by adding the
atomic and mass numbers
3.How many neutrons are there,
if the mass number is 1 and
the atomic number is 1?
A 3
B
2
C
1
D 0
3.How many neutrons are there,
if the mass number is 1 and
the atomic number is 1?
A 3 Incorrect:
There may be more or
less neutrons than protons
B
Incorrect:
2 No subatomic particle #
is found by adding the
atomic and mass numbers
3.How many neutrons are there,
if the mass number is 1 and
the atomic number is 1?
C 1 Incorrect:
There is 1 proton &
1 electron
D 0 Correct:
1-1 = 0
4.How many electrons are in
an atom of Cl?
A 17
B
18
C
35
D 0
4.How many electrons are in
an atom of Cl?
Correct:
A 17
There are 17 + charges,
so there are17 - charges
B
18 Incorrect:
35-17 = number of
neutrons
4.How many electrons are in
an atom of Cl?
C
35 Incorrect:
Mass # is the sum of
protons & neutrons
D 0
Incorrect:
All neutral atoms have
at least 1 electron
5.Which of the following is
a formula?
A H
B
O
C
H2O
D h2o
5.Which of the following is
a formula?
A H
B
Incorrect:
Symbol for hydrogen
O Incorrect:
Symbol for oxygen
5.Which of the following is
a formula?
C H2O Correct:
There are 2Elements
The ratio is 2:1
Incorrect:
D h2o 1st letter is a capital
2 is not written as a
subscript
6.How many elements are in
baking soda, NaHCO3 ?
A 6
B
5
C
4
D 3
6.How many elements are in
baking soda, NaHCO3 ?
A 6 Incorrect:
There are 6 atoms
B
Incorrect:
5
The lower case “a” is part
of the symbol for sodium
6.How many elements are in
baking soda,NaHCO3 ?
C
4 Correct:
4 elements: sodium,
hydrogen, carbon, oxygen
Incorrect:
D 3
3 is the subscript for
oxygen
Graphics
Microsoft Clip Art
Microsoft Office Online
http://www.wonderquest.com/images/2003-08-08-peroxide.jpg
http://www.cpsc.gov/cpscpub/pubs/466.html
agenthttp://members.tripod.com/duebills/27.html
http://www.wonderquest.com/images/2003-08-08-peroxide.jpg
http://www.tea.state.tx.us/student.assessment/taks/booklets/science/g8e.pdf
Isotopes
• Not all atoms of the same element have the same number of neutrons.
Most Carbon atoms have 6 neutrons, although some have more and
some have less. Atoms of the same element with differing numbers of
neutrons are called isotopes. The number of neutrons does not change
the atom or the element it makes up; it just changes the mass of the
atom. Most elements have isotopes.
Isotopes
• Not all atoms of the same element have the same number of neutrons.
Most Carbon atoms have 6 neutrons, although some have more and
some have less. Atoms of the same element with differing numbers of
neutrons are called isotopes. The number of neutrons does not change
the atom or the element it makes up; it just changes the mass of the
atom. Most elements have isotopes.