Download Chapter 18: Atoms and Elements

Integrated Science
Unit 6, Chapter 18
Unit Six: Properties of Matter
Chapter 18 Atoms and Elements
18.1 Atomic
Structure
18.2
Comparing Atoms
18.3
The Periodic Table of Elements
Chapter 18 Learning Goals









Use indirect measurement to determine the radius of a circle.
Build models of atoms.
Research one of the historical atomic models.
Understand how atoms of each element differ.
Describe the forces that hold an atom together.
Use the concept of electron shells to arrange electrons in atomic
models.
Understand how elements are organized in the periodic table.
Use the periodic table to identify the atomic number and mass
numbers of each element.
Calculate the numbers of protons and neutrons in each stable
isotope of an element.
Chapter 18 Vocabulary Terms

atomic mass electrons

neutrons

atomic mass units

nucleus

atomic number

periodic table of elements

atomic theory

protons

energy levels

strong nuclear force

group of elements

subatomic particles

isotopes

valence electrons

mass number
18.1 Atomic Structure

All matter is formed from
atoms.

If broken apart, almost all
atoms contain three
smaller particles called
protons, neutrons, and
electrons.

Protons and neutrons
cluster together in the
atom’s center, called the
nucleus.
18.1 Atomic Structure

Atoms and molecules are called
the building blocks of matter.

Atoms are very small.

Subatomic particles have charge
and mass:
— proton (p+) = 1 amu
— neutron (n0) = 1 amu
— electron (e-) = 1/2000 amu
 Most of the atom is empty space because almost all of the
mass of an atom is concentrated in its nucleus.
18.1 Changing model of the atom
John Dalton's Atomic Theory 1808
1.
2.
3.
4.
5.
6.
Each element is composed of extremely small
particles called atoms.
All atoms of a given element are identical.
Atoms of different elements have different properties,
including mass and chemical reactivity.
Atoms are not changed by chemical reactions, but
merely rearranged into different compounds.
Compounds are formed when atoms of more than one
element combine.
A compound is defined by the number, type (element),
and proportion of the constituent atoms.
18.1 Changing model of the atom

Dalton pictured the
atom as a small hard
sphere.
18.1 Changing model of the atom
 The
Thompson model
suggested negative
electrons were
embedded in a positive
sphere.
18.1 Changing model of the atom
 Bohr's
model showed
electrons moving
around the nucleus in
fixed orbits.
18.1 Changing model of the atom
 Schrödinger's
mathematical model
demonstrated that the
electron position could
be predicted, but not
pinpointed exactly.
18.1 Atomic Structure
Key Question:
How was the size of an
atom's nucleus
discovered ?
*Read text section 18.1
BEFORE Investigation 18.1
18.2 Comparing Atoms

The number of protons
determines an element.
18.2 Mass Number

The total number of protons
and neutrons in the nucleus
of an atom is called the
mass number.
18.2 Isotopes

Isotopes are atoms of the same element
that have different numbers of neutrons.
 These
are all isotopes of hydrogen.
18.2 Comparing Atoms
Key Question:
What are atoms and how
are they put together?
*Read text section 18.2
BEFORE Investigation 18.2
18.3 The Periodic Table of Elements
 Elements
are made up of only
one kind of atom.
 Compounds
are made up of
combinations of atoms.
 Elements
that are part of the
same group act alike.
18.3 The Periodic Table of Elements

Dimitri Mendeleev (18341907) organized
information about all the
known elements in a table
that visually organized the
similarities between them.

Mendeleev placed each
element on the table in a
certain row and column
based on its properties.
18.3 The Periodic Table of Elements

The chemical symbol is an
abbreviation of the
element’s name.

The atomic number is the
number of protons all
atoms of that element
have in their nuclei.
18.3 The Periodic Table of Elements

The mass number of an
element is the total
number of protons and
neutrons in the nucleus.

The atomic mass is the
average mass of all the
known isotopes of the
element.
18.3 The Periodic Table of Elements
 The
symbols for
some elements don’t
always obviously
match their names.
18.3 The Periodic Table of Elements
Key Question:
What does atomic structure have to do with
the periodic table?
*Read text section 18.3 BEFORE Investigation 18.3