what is a symbol?

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

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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

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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

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