Slide 1

Particles in the AtomParticles in the Atom

Slide 2

ElectronsElectrons (-) charge no mass located outside the nucleus

ProtonsProtons (+) charge 1 amu located inside the nucleus

NeutronNeutron no charge 1 amu located inside the nucleus

Particles in the Atom

Slide 3

Subatomic Particles

Electron

Proton

Neutron

Name Symbol ChargeRelative mass

Actual mass (g)

e-

p+

no

-1

+1

0

1/1840

1

1

9.11 x 10-28

1.67 x 10-24

1.67 x 10-24

Slide 4

Structure of the Atom

– There are two regions•The nucleus

– With protons and neutrons• Positive charge• Almost all the mass

– Electron cloud• Most of the volume of an atom• The region where the electron can be found

Slide 5

Subatomic Particles

POSIT IVECHARG E

PROT ONS

NEUT RALCHARG E

NEUT RONS

NUCLEUS

NEG AT IVE CHARG E

ELECT RONS

AT OM

Most of the atom’s mass.

NUCLEUSNUCLEUS ELECTRONSELECTRONS

PROTONSPROTONS NEUTRONSNEUTRONS Negative Charge

PositiveCharge

NeutralCharge

ATOM

Atomic Numberequals the # of...

equal in a neutral atom

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Slide 6

Size of an atom

•Atoms are incredibly tiny.

•Measured in picometers (10-12 meters)–Hydrogen atom, 32 pm radius

•Nucleus tiny compared to atom–Radius of the nucleus near 10-15 m.–Density near 1014 g/cm

•IF the atom was the size of a stadium, the nucleus would be the size of a marble.

Slide 7

Counting the Pieces

Atomic Number = number of protons# of protons determines kind of atom

Atomic Number = number of electrons in a neutral atom

Mass Number = the number of protons + neutrons

Slide 8

Symbols

Contain the symbol of the element, the mass number and the atomic number

X Massnumber

Atomicnumber

# protons

# protons + # neutrons mass number

Slide 9

Symbols•Find the

–number of protons

–number of neutrons

–number of electrons

–Atomic number

–Mass number

F19 9

9

10

9

9

19

Slide 10

Symbols•Find the

–number of protons

–number of neutrons

–number of electrons

–Atomic number

–Mass number

35

45

35

35

80

Br8035

Slide 11

Symbols•Find the

–number of protons

–number of neutrons

–number of electrons

–Atomic number

–Mass number

Na23 11

11

12

11

11

23

Slide 12

Symbols•Find the

–number of protons

–number of neutrons

–number of electrons

–Atomic number

–Mass number

V51 23

23

28

23

23

51

Slide 13

SymbolsSymbols

If an element has 60 protons and 144 neutrons what is the

–Atomic number

–Mass number

–Number of electrons

–Complete symbol

60

204

60

Nd60204