Download BohrModels and Notation

Do Now: You may use your
notes
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Who discovered protons and the nucleus?
Who discovered electrons and proposed the
plum pudding model?
Who proposed the 1st atomic model?
Who proposed the theory of electron clouds?
Who discovered neutrons?
Who proposed the model with electrons
travelling in orbits around the nucleus?
Who was the father of modern chemistry?
Who proposed the first scientific atomic
theory?
The Quantum Mechanical Model
The Nucleus
The Electron Cloud
The Nucleus
O The nucleus is the positively-charged core at the
center of an atom.
O It is TINY in comparison to the whole atom. If the
atom is the size of a football field, the nucleus is a
nickel in the middle of the field.
O It is VERY dense--within this tiny space, the nucleus
contains 99.97% of the atom’s mass.
O It contains the protons and neutrons.
The Electron Cloud
O The electron cloud is the negatively-charged region
surrounding the nucleus of an atom.
O It is VERY BIG in comparison to the whole atom. If the atom
is the size of a football field and the nucleus is a nickel in
the middle of the field, the electron cloud is the rest of the
field.
O It is NOT VERY dense at all--within this large space, the
nucleus contains only 0.03% of the atom’s mass.
O It contains the electrons. (DUH!)
Elements
O So far we have learned that an element is a pure
substance that cannot be broken down into any simpler
substances
O What can you look at to find all of the elements that
exist in our world?
O Another way to think of an element is that it is an atom
with a specific number of protons.
How to Read the Periodic Table
Element Name
Atomic Number
(# of protons)
Element Symbol
Atomic Mass
Atomic Numbers
O Atomic Number = #of Protons
O Mass Number= # of Protons + # of Neutrons
O So
# of neutrons= mass - # protons
O Atomic Number usually equals # of electrons
Look at Beryllium
O How many protons does it have?
O How many electrons does it have?
O How many neutrons does it have?
Which element has 12
protons?
O How many electrons does it have?
O How many neutrons?
Bohr Models
O Niels Bohr developed the Bohr model of atoms.
O This model looks like a solar system and is special
because it uses energy levels.
Based on the number of
protons, this is a Bohr
model for Carbon!
Bohr Model
O What subatomic particles
are in the nucleus?
O What subatomic particle is
on the energy levels around
the nucleus?
O Each energy level can hold a
specific number of
electrons:
Energy Level #
# e-’s that Fill
1
2
3
4
2
8
18
32
Calculating Charge of an Atom
Count the number of protons.
Subtract the number of electrons.
This is the charge.
O What is the charge of this atom?
On Your Own!
O Draw a Bohr model for an atom that has 4 protons, 5
neutrons, and 4 electrons
O What element is this?
O What is the charge of this atom?
O Draw a Bohr model for an atom that has 13 protons,
14 neutrons, and 14 electrons
O What element is this?
O What is the charge of this atom?
On Your Own!
O Draw a Bohr model for an atom that has 2 protons, 2
neutrons, and 2 electrons
O What element is this?
O What is the charge of this atom?
O Draw a Bohr model for an atom that has 10 protons,
10 neutrons, and 10 electrons
O What element is this?
O What is the charge of this atom?
Recap: Calculating Subatomic
Particles
O # of protons = atomic number
O # of electrons = atomic number
O # of neutrons = atomic mass – atomic number
Atomic Notation
O How do scientists write element names?
Nuclear Notation
Mass Number
Atomic Number
Nuclear Notation
Nuclear Notation
Nuclear Notation
O Fill in the table for the following atoms:
O A lithium atom with a mass number of 7
O An atom with 7 protons and a mass number of 14
O An atom with 22 electrons and a mass number of 47
O A platinum atom with a mass number of 194
O An arsenic atom with a mass number of 75
Isotope Notation
O Isotope notation is even easier!
NAME OF ELEMENT – mass #
Comparing Nuclear and
Isotope Notation
O How are they similar?
O How are they different?
Calculating Mass Number
O Because an atom is so small, we have a special unit
to represent its mass.
O The mass of an atom is found in atomic mass units,
or amus.
Proton
Mass
1 amu
Electron
0 amu
Neutron
1 amu
Calculating Mass Number
On Your Own!
O Calculate the masses of Fluorine, Sodium, and Zinc
(Examples 7-9).