Chapter 17

```Chapter 17
Properties of Atoms and
the Periodic Table
Section 1 – Structure of the Atom

Look at elements and their symbols
What’s in an atom?
Atom: smallest piece of matter that still
is the __________________
 Nucleus: ______________________
charged center of atom containing

– Protons: particle with _________ charge
– Neutrons: particle with ________ charge

Electrons: surround nucleus in cloud
and have ______ charge
Even smaller…
______________: make up protons and
neutrons NOT electrons
 Found using a __________________
accelerator

– Speed up particles and ______________
them into each other
– Found ____ quarks
Models
Represent things that are hard to
_______________
 Model of the _______________ has
changed many times
 Pg. 510 in book

Today’s model of atom

Electron ________________ model:
nucleus in middle and cloud around
nucleus where electrons are most
________________ found
Section 2
Atomic Masses
Masses of Atoms

Nucleus has most of mass
– _______________ : 1.6726 x 10-24 g
– Neutron
: 1.6749 x 10-24 g
– _______________: 9.1093 x 10-28 g

Mass of proton and neutron are about
________________ times bigger than
electron!!
Atomic Mass
Need ______________ numbers for
masses
 Atomic ___________ Unit (amu)
 Proton: 1 amu
 Neutron: ___ amu
 Electron ~ negligible

Protons Identify Element
Each element has different # of
____________________
 The number of protons tells you what
type of _____________________ you
have
 Atomic Number: the number of
_____________

Mass Number
Mass Number: ____________ of
protons and neutrons
 # of neutrons = mass # - __________ #
 Carbon – 12 and Carbon – 14

Mass Number
Mass Number
How many neutrons are in the Carbon14 atom?
 Sodium has a mass number of 23. How
many protons and neutrons does it
have?
 Copper – 63: how many protons and
neutrons?

Isotopes
Def: atoms of the same element that
have different # of ____________
 Isotopes: Boron – 10 and Boron – 11
 Average Atomic Mass:
________________ average mass of
mixture of isotopes

Calculating Average Atomic
Mass

Four out of five boron atoms are boron11 and one out of five are boron-10.
What is the AAM?
Section 3
The Periodic Table
Organizing the Elements
__________________ – repeated in a
pattern
 Late 1800s – Dimitri Mendeleev –
Russian – organized elements by
increasing ______________
 Discovered a pattern with chemical
__________________, they repeated
 Periodic

Mendeleev’s Periodic Table
Current Periodic Table

1913 – Henry Moseley – English –
organized elements by increasing
________________________
The Atom and the Periodic Table
Vertical columns = _______________ /
Families
 Use A group numbering
 Families have _________________
properties

Location of Electrons
In neutral atom, # of _______________
= # of electrons
 Energy levels

– close to nucleus = ___________ energy
– farther away = _____________ energy
Energy Levels and Electrons
Same group = same # of _________ in
_______________ energy level
 Energy levels are 1 – _____
 Filled outer energy level = ________
 Levels 3 and higher have __________
sub-levels

Energy Levels and Electrons
Horizontal rows = _____________
 Increase by 1 p+ and 1 e- as you move
______________
 Each row ends with atom with
_______________ outer energy level

Electron Dot Diagrams
Group #s = # ________________ e-s
(outer e-s)
 Def: uses the element _____________
and dots to represent outermost
____________________
 Atoms bond to get a _______________
outer energy level
 Which groups would likely react?

Regions of the
Periodic Table
Metals, Non-metals, and
Metalloids
Metals

Conductors of ___________ and
electricity
 Luster/___________
 Mostly solid
Nonmetals

_________ conductors of heat and
electricity
 Many are gases
 Solids are _________
Metalloids
• _________________
of heat and electricity
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