Organization of The Periodic
Table
Open to page 112 and 113.
Nucleus
• Center of the atom.
• Makes majority of the atom’s mass.
• Made of protons and neutrons.
Protons
• Part of the nucleus
• Have positive (+) charge
Neutrons
• Part of the nucleus
• Have neutral charge
Electrons
• Orbit around the nucleus
• Have negative (-) charge
Atomic Number
• Definition: the number of protons in the
nucleus
• Tells us the identity of the element.
Mass
Every element is defined by the number of protons in its nucleus
Isotopes
• Atoms with the same number of protons
but different numbers on neutrons
• Example: Carbon
So you can change the number of neutrons and the element still maintains its identity
Questions
• 1) What particles make up an atom?
• 2) What are the charges on these
particles?
• 3) What particles make up the nucleus?
Questions
• 1) What is Oxygen’s atomic number?
• 2) How many protons does Oxygen have?
• 3) If I have 4 protons what element am I?
• 4) If I have 4 neutrons what element am I?
Reading the Periodic Table
Mass
Atomic Mass
• Definition: the mass of one atom of an
element
• Tells us how much one atom weighs in
atomic mass units.
Mass
Assignment
• Read p. 109 – 117
• Complete Section 2 Assessment
#1-3
Atoms have neutral charge
• # of Protons (+) = # of Electrons (-) = 0 charge
• Example: Hydrogen
• How many electrons does C have?
Organization of The Periodic Table
Group/Family
Period
Ordered by atomic mass. Columns arranged to form groups with similar properties
Assessment
• Which element has the greatest atomic
mass?
• Lithium
• Sodium
• Potassium
• Rubidium
Reactivity
• The ease and speed
with which an element
combines, or reacts,
with other elements or
compounds
Pure sodium reacts explosively
with air
Groups/families of elements have similar reactivity
Group 1: metals that react violently with water
Group 18: Gases that barely react at all
Why do groups/families of elements react the same way?
Take home message
• The properties of an element can be
predicted from its location on the Periodic
Table
• This is largely a result of the number of
electrons.
Question
• How many electrons does an oxygen
have?
Metals, Metalloids, and Nonmetals
Metals
• Shiny
• Solids (at room temp)
• Malleable – can be
hammered flat
• Ductile – can be pulled
into wire
• High Conductivity –
ability to transfer heat or
electricity to another
object
Reactivity of Metals
High
Low
Metals will usually lose electrons when they react with other elements
Magnesium reacting to water.
Sodium reacting to water.
Alkali Metals
• Metals in Group 1
• Often lose an electron when they react
with other elements
• Most Reactive: Rare to find them in their
pure form because they are so reactive
• Very shiny and soft
• Example: Lithium batteries
Potassium in its pure form
Alkaline Earth Metals
• Group 2
• Hard, gray-white, good conductor of
electricity
• Lose 2 electrons when they react with
other elements
• Hard to find in pure form.
• Example: Calcium in your teeth
and bones.
Calcium in its pure form
Transition Metals
• Groups 3 – 12
• Hard, shiny, good conductors of electricity
– Can form colorful compounds
• Less reactive
• Examples: iron, gold, copper, nickel
Pure iron
Pure copper
Groups 13-15
• Only some are metals
• Not very reactive
• Examples: aluminum, tin, lead
Pure
aluminum
Pure lead
Lanthanides
• 1st row below the Periodic Table
• Soft, malleable, shiny metals
• Often mixed with other metals to make
alloys
Pure cerium
Pure
Samarium
Actinides
• 2nd row below the Periodic Table
• Only the first six naturally occur on Earth
• The other elements are synthetic and
unstable
– Some only exists for a few seconds after
being made
Depleted uranium
Assignment
• Worksheet
• “Elements and the Periodic Table”
Assignment
• Go on a metal scavenger hunt at your
house, school, etc…
• Make a list of 10 metals you find
– Identify each metal and the group it belongs
to.
– You cannot write down the same metal more
than twice!
Example
Item
Type of Metal
Group
Mom’s wedding ring
Gold, Transition Metal
11
Nonmetals
• Opposite of properties
of metals
• Not shiny
• Poor conductors
• Mostly gases (at room
temperature)
• Solids are brittle
Sulfur
Reactivity of Nonmetals
Low
Low
High
Nonmetals will usually gain or share electrons when they react with other elements
Some Important Nonmetals
• Carbon – important element for making up
living organisms
• Noble Gases – group 18 – very
nonreactive. Have full outer shells.
Metalloids
• Inbetween metals and
nonmetals
• Solids (at room temp)
• brittle and hard
• Semiconductors – can
conduct electricity under
some conditions but not
others.
– very important for
computer chips
• Most common example –
Silicon – in sand and
glass
Assessment
• The atomic number is the number of
– valence electrons.
– neutrons.
– protons in the nucleus.
– electrons in the nucleus.
Assessment
• The periodic table is a chart of the
elements that shows the repeating pattern
of their
– energies.
– properties.
– element symbols.
– names.
Assessment
• Which piece of information cannot be
found in a square on the periodic table?
– Atomic mass.
– Chemical symbol.
– Atomic number.
– Number of neutrons.
Assessment
• Which element will have properties most
similar to Calcium?
– Potassium.
– Scandium.
– Magnesium.
– Bromine.
Assessment
• Which group is most likely to lose/share 2
electrons in a chemical reaction?
–1
–2
– 17
– 18
Assessment
• Which side of the periodic table contains
most of the nonmetals?
– Left side
– Right side
– Middle
Assessment
• Which is not a property of nonmetals?
– Brittle
– Nonmalleable
– High conductivity
– Most are gases at room temperature
Assessment
• Which metal is probably the most
reactive?
– Potassium
– Calcium
– Scandium
– Titanium
Assessment
• Which nonmetal is probably the most
reactive?
– Nitrogen
– Oxygen
– Fluorine
– Neon