Structure of the AtomStructure of the Atom

Chemical symbol-Chemical symbol- an an abbreviated way to write abbreviated way to write the name of an element.the name of an element.

Ex: C= Carbon O= OxygenEx: C= Carbon O= Oxygen

H= Hydrogen H= Hydrogen

N= NitrogenN= Nitrogen

Al= Aluminum Au= GoldAl= Aluminum Au= GoldPg. 556-557(Periodic Table)Pg. 556-557(Periodic Table)

Inside the AtomInside the AtomInside the atom is the Inside the atom is the nucleus. The nucleus. The nucleusnucleus contains contains protons and protons and neutronsneutrons while while surroundingsurrounding the the nucleus are the nucleus are the electronselectrons..

Electron →

(e-)

←Electron

(e-)

← Protons &

← Neutrons

(p+) & (n0)

Protons has a Protons has a positive positive charge.charge. (p+) (p+)

Neutrons has Neutrons has nono charge. charge.

(n(n00))Electrons has a Electrons has a negativenegative charge. charge. (e-)(e-)

Since there are protons Since there are protons and neutrons in the and neutrons in the atom, the net atom, the net chargecharge of the of the nucleusnucleus is is positivepositive. .

The nucleus contains The nucleus contains most of the mass of the most of the mass of the atom.atom.

The overall charge of The overall charge of the atom is neutral the atom is neutral (no charge).(no charge).

Atomic NumberAtomic NumberAtomic number-Atomic number- the the number of protons in number of protons in the nucleus of an atom.the nucleus of an atom.

The The numbernumber of of protonsprotons equalsequals the the numbernumber of of electronselectrons..

Atomic Number, # of pAtomic Number, # of p++ and and ee--

Atomic#Atomic# p p++ e e--

Oxygen=Oxygen=Hydrogen=Hydrogen=Carbon=Carbon=Aluminum=Aluminum=Gold=Gold=

Atomic Number, # of pAtomic Number, # of p++ and and ee--

Atomic#Atomic# p p++ e e--

Oxygen=Oxygen= 88 88 88

Hydrogen=Hydrogen= 11 11 11

Carbon=Carbon= 66 66 66

Aluminum=Aluminum= 1313 1313 1313

Gold=Gold= 7979 7979 7979

Atomic MassAtomic MassAtomic Mass-Atomic Mass- The The number of number of protonsprotons and and neutronsneutrons..

Round atomic mass to Round atomic mass to nearest whole number.nearest whole number.

To calculate the number To calculate the number of neutrons, subtract the of neutrons, subtract the atomic number from atomic number from atomic mass.atomic mass.

Calculate the number of Calculate the number of neutronsneutrons

OxygenOxygen Carbon Carbon Boron Boron

pp++&n&noo 1616 1212 1111

pp++ -8-8 -6-6 -5-5

nn oo 8 8 6 6 6 6

Atomic mass=(# of pAtomic mass=(# of p++&n&noo))

Atomic number= (# of pAtomic number= (# of p++))

Electron Cloud-Electron Cloud- a a region where the region where the electrons move electrons move around. It surrounds around. It surrounds the nucleus of the the nucleus of the atom.atom.

Electrons close to the Electrons close to the nucleus have low nucleus have low energy while electrons energy while electrons farther away have farther away have more energy.more energy.

Electrons are placed Electrons are placed into energy levels.into energy levels.

Energy LevelsEnergy Levels

Energy LevelEnergy Level Max # of eMax # of e--

11 22

22 88

33 88

44 1818

Nucleus p+ & no

e-

e-

e- e-

e- e-

e- e-

e- e-

e-e-

e-e-

e-e-

e-e-

←3rd = 8 e-

←2nd = 8 e-

←1st = 2 e-