The Bohr Model of the Atom

DO NOT WRITE ON THESE NOTESCOPY THESE NOTES IN CORNELL

STYLE IN YOURBINDER.

What do we need to know?

• Atoms have 2 main parts

– Electron cloud -- contains electrons

– Nucleus – central part of the atom, contains protons and neutrons

Subatomic particles

• Symbols for each subatomic particle

– Electrons = e- (found in the electron cloud)– Protons = p+ (found in the nucleus)– Neutrons = n0 (found in the nucleus)

What do you need to know?

• Orbitals are found around the nucleus

– There are 7 possible orbitals

– Orbitals are determined by looking at what PERIOD (row) the element is in

– The orbitals hold a specific number of electrons (which is the same as the atomic number)

Period 1

Period 2

Period 3

Period 4

Period 5

Period 6

Period 7

How many electrons per orbital?Period 1 orbital (ring) 1: 2 e-

Period 2 orbital (ring) 1: 2 e- orbital (ring) 2: 8 e- Period 3 orbital (ring) 1: 2 e- orbital (ring) 2: 8 e- orbital (ring) 3: 8 e- Period 4 orbital (ring) 1: 2 e- orbital (ring) 2: 8 e- orbital (ring) 3: 18 e-

orbital (ring) 4: 8 e-

Information to create a Bohr model

• Element name and symbol:– Magnesium (Mg)– Atomic number: 12– Atomic mass: 24– Protons: 12– Electrons: 12– Neutrons: (24 - 12) = 12

12

Mg

24.305

Magnesium

Atomic # = Protons and Electrons

Atomic Mass

Atomic Mass – Atomic # = Neutrons

Bohr model for Mg

12p+

12n0

Nucleus

Orbital 1 can only hold a maximumof 2 electrons

Orbital 2 can only hold a maximum of 8 electrons

Orbital 3 can only hold a maximum of 8 electrons, but you only use the # of electrons you need.

Electrons are represented by the dots.

Magnesium will have 3 orbitals because it is in period #3

When you add all the dots (electrons) you should get 12.

Bohr model for Al

• Aluminum is in period #3 and has 13 electrons.

13p+

14n0

Your Assignment!This goes on a separate piece of

paper!• Create the Bohr model for elements 1-20 on the

periodic table. (Hydrogen (H) – Calcium (Ca))

• For each element provide the: – Write the element name: __________________– Protons= ____– Electrons= ____– Neutrons= ____– Period = _____ = Orbitals= _____– Bohr Model: