Transcript Elements, Compounds & mixtures

ATOMS AND THE
PERIODIC TABLE
Pages 311 - 352
 What are
the parts
of an
atom?
 Nucleus – The center of the
atom. It contains…
 Protons – Positively charged
particles.
 Neutrons – that have no
charge.
 Outside the nucleus…
 Electrons – Negatively
charged particles.
 Every atom of the same
element has the same
number of protons.
 What is
the
Periodic
Table?
 It’s an arrangement of
elements showing the
repeating pattern of
properties.
 Created by Mendeleev
 He grouped them
according to chemical
and physical properties.
 How do
you read
the
Periodic
Table?
 For each element it tells the
Atomic Number, the Atomic
Mass, The Chemical Symbol,
and the Chemical Name.
 The Atomic Number tells the
number of protons (and
usually the number of
electrons)
 Atoms with a different
number of electrons than
protons are called ions and
are electrically charged
particles.
 What is
Atomic
Mass?
 It is the average mass of
all the isotopes of that
element.
 (Remember, an Isotope is
an element that has the
same amount of protons
but a different amount of
neutrons changing it’s
mass.)
 How is the
Periodic
Table
Useful?
 An element’s properties can
be predicted from looking at
its location in the Periodic
Table.
 Atomic Numbers are in order
from left to right, and similar
properties are grouped
together in columns.
 What is a
period?
 A row on the Periodic Table.
 Properties change in a
predictable way as you go
from left to right.
 Metals are shown on the left
and nonmetals on the right
with metalloids in the middle.
 What is a
Group?
 The elements in a column
form a group.
 Each group is known as a
family.
 The Elements in each group
have similar characteristics.
 For example – all elements in
group 1 (except for hydrogen)
are metals that react
violently with water.
 How are
elements
grouped
together?
 The elements are
grouped together in three
main categories:
 Metals
 Nonmetals
 Metalloids
 What are
the
properties
of metals?
 Physical:
 High luster – shiny and
reflective
 Malleable – can be
hammered into flat sheet
 Ductile – can be pulled out or
drawn into a wire
 Thermal conductivity – can
transfer heat
 Electrical conductivity – can
transfer electricity
 Properties
of metals
cont…
 Chemical:
 Reactivity – the ease or speed
that elements react or
combine with other
elements. Most metals react
by losing electrons to other
atoms.
 Corrosion – the gradual
deterioration of a metal due
to a chemical reaction with
the environment.
 How are
metals
classified?
 Metals are classified into






6 categories:
Alkali metals
Alkaline earth metals
Transition metals
Metals in mixed groups
Lanthanides
Actinides
 What are
Alkali
Metals?
 They are VERY REACTIVE!!!!!
 The metals in group 1 from
lithium (li) to francium (Fr)
 They are never found by
themselves in nature –
always in a compound.
 They are shiny and very soft –
some can be cut with a plastic
knife!
 They have low densities and
low melting points – ex.
Sodium melts at 98 C and is
less dense than water!
 Alkaline
Earth
Metals
 Reactive – but not as reactive
as the alkali metal group.
 They are more dense and
melt at higher temperatures
– ex. Magnesium (Mg) melts
at 648.8 C.
 Calcium is one of the most
common alkaline earth
metals – needed for healthy
bones.
 Transition
 Most are hard and
metals





shiny solids (except for
Mercury which is a
liquid at room temp.)
Includes iron, copper,
nickel, gold and silver.
High melting points
and high densities.
Good conductors
Very malleable
Less reactive than 1-2
 Metals in
 Only some of elements
mixed
groups
in groups 13 – 16 are
metals.
 Include Aluminum, Tin,
Lead.
 Not very reactive –
used to coat other
metals so they won’t
corrode.
 Lanthanides  Many of these
and
Actinides
elements are synthetic
(not naturally found
but artificially made in
laboratories).
 They are made using
particle accelerators.
 Transuranium  The synthesized
Elements
elements found on the
table past Uranium.
They are made by
crashing the nuclei of
atoms together at
extremely high speeds
using particle
accelerators.
 What are
the
properties
of
Nonmetals?




Physical:
Dull
Brittle
Poor conductors of
both heat and
electricity.
 Nonmetals
cont….
 Chemical Properties:
 Atoms of nonmetals
usually gain or share
electrons with other
atoms. Electrons
move from metals to
nonmetals.
Sometimes nonmetals
join together to form
compounds such as
H2O
 Families
containing
Nonmetals

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



The Carbon Family
The Nitrogen Family
The oxygen Family
The Halogen Family
The Noble Gases
Hydrogen
 The Carbon
family
 Group 14
 Most fuels used to
yield energy contain
carbon such as coal,
gasoline, crude oil.
 Carbon is important to
life – proteins, carbs,
DNA, fats.
 Diamonds are pure
carbon.
 Nitrogen
family
 Group 15
 Contains 2 nonmetals
– Nitrogen and
Phosphorous.
 Oxygen
family
 Group 16
 Contains 3 nonmetals
– Oxygen, Sulfur, and
Selenium. O – gas
 S & Se - solids
 Halogen
family
 Group 17
 Nonmetals include
Florine, Chlorine,
Bromine and Iodine.
 Halogen means “salt
forming”
 Although halogen
elements are
dangerous – they are
useful – water
treatment, toothpaste.
 The Noble
Gases
 Group 18
 Usually nonreactive.
 Helium (He), Neon
(Ne), Argon (Ar),
Krypton (Kr), Xenon
(Xe).
 Used in Balloons and
Neon lights.
 Hydrogen
 Alone in the upper left
corner of the Periodic
table.
 Properties very
different than all
others, so it is not
grouped with a family.
 Hydrogen makes up
more than 90% of all
atoms in the universe,
but only 1% on Earth.
 What are
Metalloids?
 They have some
properties of metals
and some of
nonmetals.
 Solids
 Brittle, hard,
somewhat reactive.
 Semiconductors
(conduct electricity
under certain
conditions)
 Models 0f
atoms….
 Notes…..