Transcript ATOMS AND THE PERIODIC TABLE chapter three

ATOMS AND THE PERIODIC
TABLE
chapter three
FOCUS ACTIVITY 1
METAL
Copper
USE
Money
PROPERTY
durable
ATOMIC THEORY - history
4TH CENTURY
B.C.
Matter is made of tiny
particles called ATOMS.
John
DALTON
EARLY 1900’s
(1913)
MID 1900’s
Modern
(after 1925)
theory
ELEMENTS are made
of particles called atoms.
ATOMS of the same
elements are alike.
ATOMS form molecules.
ELECTRONS orbit like
planets in the solar system.
ATOMIC THEORY - STRUCTURE
MODEL OF THE ATOM
ENERGY
LEVELS
ELECTRON
-
NUCLEUS
PROTON
+
NEUTRON
(NEUTRAL)
ATOMIC STRUCTURE
ELECTRON LOCATION
Electrons are found in energy
levels of an atom.
Electrons occupy the lowest
energy level available.
Bohr’s Atom and Energy Levels
Energy Levels are like ladder rungs…
GAINING
ENERGY
GOOD
BETTER
Energy Levels
ORBITALS – where the _____ are
located within an energy level.
S orbital
(Like a sphere)
may contain up
to 2 electrons
first energy
level is an s orbital
1s and 2s orbitals
P orbital
(Like a dumbbell)
may contain up to 2
electrons
second energy level
may contain an s
orbital and up to 3 p
orbitals
Orbitals
_____ electrons are located in the
outermost energy level of an atom.
They determine the
chemical properties
of an element.
3.2 A TOUR OF THE PERIODIC
TABLE
• Properties of elements change in a regular
pattern that the table helps to describe.
• Periods –
• Groups(families) -
Los Alamos National Laboratory:
Periodic Table
Traditional Periodic Table
A Spiral Vision of the Periodic Table
of the Elements
The number of protons in an atom
determines an element’s location
on the table.
Los Alamos National Laboratory: Periodic
Table
ATOMIC
NUMBER
6
PROTONS
(and ELECTRONS too)
SYMBOL
NAME
MASS
C
Carbon
12.001
PROTONS
+ NEUTRONS
MASS #
1
1
PROTONS AND NEUTRONS
HAVE EQUAL MASS.
ELECTRONS ARE TINY – 1800
EQUAL ONE PROTON.
1800
1
MASS
ATOMIC NUMBER
35 Cl
17
protons _?_ electrons _?_
neutrons _?_
IONS are atoms that have lost or
gained an ___.
• ELECTRON GAINED =
NEGATIVE CHARGE
(-)
ELECTRON LOST =
POSITIVE CHARGE
(+)
Electron
transfer
Na+
Cl
TWO KINDS OF IONS:
A (+) CHARGED
ION IS A ____.
A (-) CHARGED
ION IS AN ___.
EXAMPLES:
• LITHIUM
• FLUORIDE
The atoms of an element always
have the same number of protons.
BUT…..
The atoms of an element may have
different numbers of neutrons.
This is an ISOTOPE!
Two carbon ISOTOPES:
CARBON 12 = 6 protons and 6 neutrons
CARBON 14 = 6 protons and 8 neutrons
The AVERAGE MASS of an ATOM
• Why is the mass number not an even
number?
– Atoms of the same element exist with
different numbers of neutrons.
– This makes the mass of different atoms of
the same element different.
– The average mass is a weighted number so
that more common isotopes have a greater
affect on the average than rare isotopes.
• What is an amu?
– It is an “atomic mass unit”.
– An amu is equivalent to the mass of 1/12 of
a carbon-12 atom.
3.3 FAMILIES OF ELEMENTS:
• HAVE THE SAME VALENCE NUMBER.
• HAVE SIMILAR CHEMICAL AND
PHYSICAL PROPERTIES.
• A COLUMN OF ELEMENTS IS A
FAMILY.
TWO MAJOR DIVISIONS
• METALS
• NONMETALS
GROUP ONE:
ALKALI METALS
• VERY REACTIVE
• ONE VALENCE
ELECTRON
GROUP TWO:
ALKALINE EARTH METALS
• TWO VALENCE ELECTRONS
GROUP 3-12:
TRANSITION METALS
• MANY COMMON METALS
• NOT AS REACTIVE AS OTHER
METALS
GROUP 17:
HALOGENS
• VERY REACTIVE
• FORM SALTS WITH ALKALI METALS
• 7 VALANCE ELECTRONS
GROUP 18:
NOBLE GASES
• INERT / UNREACTIVE
• EIGHT VALENCE ELECTRONS
SYNTHETIC ELEMENTS
• They are man-made and radioactive.
• They include all elements above #92, plus
#43 and #61.
SEMICONDUCTORS
(METALOIDS).
The elements that are between the metals and
nonmetals are known as:
SEMICONDUCTORS (METALOIDS)
They may exhibit metallic and nonmetallic
properties.
B
Si
Ge
As
3.4 USING MOLES TO COUNT ATOMS
• Some counting units:
–
–
–
–
Reams of paper
Dozens of eggs
Atomic mass units of protons and neutrons
Moles of atoms
• A mole is the SI unit that describes the amount of a
substance.
• Avogadro’s constant is the number of particles in
one mole which = 6.022 x1023
• molar mass is the mass in grams of one mol of a
substance…it is equal to the average atomic number
of an atom.
Chapter 3
Studying for the Test
•
•
•
•
•
•
Vocabulary
Parts of an atom
History
Element families
Using the periodic table
Metal vs. nonmetal