What is a Symbol?
Elements and Chemical Symbols
Chemical Symbols / Element Names
H
Hydro
gen
OOxygenCo
Cobalt
Cl
Chlor
ine
CCarbon
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
Co or CO
Does it really matter?
Co
Cobalt-60, extensively used as a tracer and a radiotherapeutic
http://members.tripod.com/duebills/27.html
Co
Required in soils growing animal feed
Alloys for metals used in jet turbines
Co
CO
http://www.cpsc.gov/cpscpub/pubs/466.html
Kills 200 People
in United States
COProduced by IncompleteBurning of Fossil Fuels
carbon monoxide ColorlessOdorlessPoisonous gas
carbon oxygen
COCompound
Think beforeyou write aElement’sSymbol
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 thePeriod Table
Use your copy of the Periodic Table of Element
Correctly write the symbol for:
1.Carbon2.Nitrogen3.Oxygen4.Iron5.Chlorine
CNOFeCl
Atomic Number
Number of Protons in everyAtom of that Element
What is the name of the element with the following
number of protons?
A.2B.6C.8D.11E.47
Helium
Carbon OxygenSodiumSilver
Use th
e
Perio
dic T
able
Atomic Mass Number
Protons + Neutrons
1. Round the Mass Number to the nearest whole number
Round to 28
To calculate # of neutrons
Atomic Mass NumberProtons + Neutrons
2. Subtract Atomic NumberFrom Mass Number
28 (Mass #)
-14 (Atomic #) 14 Neutrons
Calculate # of neutrons
Protons + electrical charge
NeutronNo electrical charge
Electrons- electrical charge
+
-
Neutral Atoms(Atoms without Electric Charge)
Have equal numbers of:
Protons (+ charges)
Electrons (- charges)
How many electrons?
1 proton
9 protons
99 protons
1 electron
9 electrons
99 electrons
Use the Periodic Table and Math Skills
to fill in the blanksSymbo
lAtomi
c #
Mass #
#Proton
s
#Neutron
s
#Electron
s
He 2 4 2
3 7 3 3
N 7 7 7
Symbol
Atomic #
Mass #
#Proton
s
#Neutron
s
#Electron
s
He 2 4 2 2 2
Li 3 7 3 4 3
N 7 14 7 7 7
# protons is the atomic #protons + neutrons = mass ##electrons = # protons
Compounds2 or More Elements
Chemically Combined
Oxygen
Hydrogen Hydrogen2-H: 1-O
Water
HH
O
Ratio 2:1
Formulas use element symbolswith subscript numbers
H2O
1 is notshown
Change the ratioChange the substance
2:2
H2O2
Subscript numbers
http://www.wonderquest.com/images/2003-08-08-peroxide.jpg
HydrogenPeroxide
No subscripts??
NaCl1Na 1Cl
How many elements?
Salt
2
Sugar
C6H12O6
How many elements?3
How many hydrogen atoms?12
√ Check yourunderstanding
Use your
Periodic
Table
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: 1st letter is always
a capital
1. The symbol for carbon is –
C CA Incorrect:C is carbonThere is no
element with the symbol A
D C
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
B 12
Correct:atomic # is 11
Incorrect:12 is the number ofneutrons
2. How many protons are in an atom of sodium?
C 23
D 34
Incorrect:23 is the mass number
Incorrect:No subatomic particle #is found by adding theatomic and mass numbers
3.How many neutrons are there,if the mass number is 1 andthe atomic number is 1?
A 3
B 2
C 1
D 0
3.How many neutrons are there,if the mass number is 1 andthe atomic number is 1?
A 3
B 2
Incorrect:There may be more or less neutrons than protons
Incorrect:No subatomic particle #is found by adding theatomic and mass numbers
3.How many neutrons are there,if the mass number is 1 andthe atomic number is 1?
C 1
D 0
Incorrect: There is 1 proton & 1 electron
Correct: 1-1 = 0
4.How many electrons are inan atom of Cl?
A 17
B 18
C 35
D 0
4.How many electrons are inan atom of Cl?
A 17
B 18
Correct: There are 17 + charges, so there are17 - charges
Incorrect:35-17 = number of neutrons
4.How many electrons are inan atom of Cl?
C 35
D 0
Incorrect:Mass # is the sum of protons & neutrons
Incorrect:All neutral atoms haveat least 1 electron
5.Which of the following isa formula?
A H
B O
C H2O
D h2o
5.Which of the following isa formula?
A H
B O
Incorrect:Symbol for hydrogen
Incorrect:
Symbol for oxygen
5.Which of the following isa formula?
C H2O
D h2o
Correct:There are 2Elements The ratio is 2:1
Incorrect:1st letter is a capital2 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
B 5
Incorrect:There are 6 atoms
Incorrect:The lower case “a” is partof the symbol for sodium
6.How many elements are in baking soda,NaHCO3 ?
C 4
D 3
Correct:4 elements: sodium, hydrogen, carbon, oxygenIncorrect:
3 is the subscript for oxygen
GraphicsMicrosoft Clip ArtMicrosoft 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
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