Download Advances in Atomic Theory

Name: ____________________________
Date: ______ Per: _______
Properties and Interactions of Matter
Advances in Atomic Theory
Democritus (400 B.C.) - was the first person to
use the term “________” to describe the tiny
units of matter that make up all things.
ATOM  Derived from the Greek word
“________”meaning unable to ______
 Smallest part of an element
1. Ancient Greek Model of the Atom
Aristotle proposed the existence of the four
elements:
_______, ____, ______, _______. All matter was
a __________________ of those elements.
(Draw Ancient Greek model of the four elements)
2. Thompson’s Plum Pudding Model of
the Atom
John Dalton (1803) English chemist who
developed the first ________________ of atoms
based on laboratory experiments.
J.J. Thompson (1897) English physicist who
discovered a _________ charged subatomic
particle.
Thompson named this particle the ___________.
(Draw Plum Pudding Model of the Atom)
3. Rutherford’s Positive Nucleus
Model of the Atom
Ernest Rutherford (1911) - Gold foil experiment
showed that atoms have a ______ but _______
center called the _______________.
The nucleus contains positively (+) charged
__________ and neutrally charged ___________.
(Draw Positive Nucleus Model of the Atom)
4. Bohr’s Electron Shell Model of the
Atom
Neils Bohr (1913) - Danish physicist who showed
that electrons __________ the nucleus in welldefined orbits called ____________________.
( Draw Electron Shell Model of the Atom)
Draw for Carbon
5. Electron Cloud Model of the Atom
Electron Cloud Model (1926) - electrons move
about around the nucleus in a region called an
________________. It describes the region where
an electron is _________________ to be.
(Draw Electron Cloud Model of the Atom)
Unit Four Introduction: Properties and Interactions of Matter
Parts of an Atom
An atom consists of two parts:
1) _________ – positively (+) charged center that has
 __________ - (+) charge
 __________ - no charge
(Mass of protons and neutrons is __________ )
2) ________________ - surrounds nucleus
 ____________ – negative (-) charge
Electron Cloud Model
 electrons _______ nucleus have ______ energy
 electrons __________ away have ___________ energy
 each region (energy level) can hold
a _____________ number of electrons
Energy Levels
1 (lowest energy)
2
3
4
Max # of Electrons
In an atom, the number of protons (+) __________ the number of
electrons (-). Therefore, the atom is electrically ______________.
Atomic Number
The number of __________ in the nucleus
(In a _______ atom, this also equals the number of ___________ )
Masses of the Atoms
Mass of proton or neutron is about ______________ the
mass of an electron. Most of the mass of an atom is a result of the
protons and neutrons.
Mass Number
The sum of the number of ___________ and the number of
______________ in the nucleus of an atom
Ex. Sodium, Na
11 P
12 N
Mass #
Lead, Pb
82 P
125 N
Mass #
If Uranium has a mass # of 238 how many neutrons does it have?
Mass # = # protons + # neutrons
# neutrons = mass # - # protons
# neutrons =
_____ - ____
# neutrons =
______
Given the table below, fill in the missing information.
ELEMENT
AT. #
# PROT.
# NEUT.
Boron
Carbon
Oxygen
Sodium
Copper
Iron
Sulfer
5
6
5
6
6
8
12
8
11
29
26
29
# ELEC.
6
16
11
29
MASS #
11
12
23
63
56
32
AT. MASS
10.81
12.01
16.00
22.99
63.55
55.85
32.07
Atoms of a particular element must always have the same number
of ___________ but the number of _____________ may vary.
Isotopes - Atoms of the ________ element that have different
numbers of __________________.
Isotopes can be written two ways:
1. The name of the element followed by the mass number.
Ex. Carbon - 12
2. The chemical symbol with the mass number as a superscript
Ex. 12C
Given the isotopes listed below, enter the correct number of
protons, neutrons, and electrons for each.
Hydrogen - 1 or 1H
#P =
#N =
#E =
Hydrogen - 2 or
#P=
#N=
#E=
Hydrogen - 3 or
#P =
#N =
#E =
2
H
3
H
Average Atomic Mass
The ______________________ of all the isotopes of
an element. This value is the same as the atomic mass listed
on the periodic table.
Ex. CARBON
ELEMENT MASS
ABUNDANCE
Carbon-12
12.000
98.89%
Carbon-13
13.003
1.11%
Average Atomic Mass 
Ex. OXYGEN
ELEMENT
MASS ABUNDANCE
Oxygen- 16
15.995
99.76%
Oxygen- 17
16.999
0.04%
Oxygen- 18
17.999
0.20%
Average Atomic Mass 