Transcript Periodic table

Atoms and the Periodic Table
Basic Definitions
 Chemistry
 is the study of the composition, structure, and
properties of matter and the changes it undergoes.
More Intro Stuff
 Chemistry can deal with questions like:
 What is this material made of?
 What type of things will this substance react with?
 Why is carbon dioxide transformed by plants into
oxygen?
17.1
 Atom: is the smallest unit of an element that has
the same properties of that element.
 Element: is a pure substance composed of only
one kind of atom.
 Compound: is a substance that is made of two or
more elements that are chemically bonded
together.
Atoms are old!
 Hydrogen is the oldest and most abundant element
 The atoms in your body existed since the beginning of
time
 We recycle atoms!
Atoms Composition
 Protons – positive parts in the nucleus
 Neutrons- neutral parts in the nucleus
 Electrons- small negative parts around the nucleus
 The movement of electrons is electricity!
Periodic Table
 Periodic table: is a grouping of elements in order of
increasing atomic number.
 Atomic symbol: the letters by which the element is
designated
 Frequently from the Latin name
 First letter capital, second lowercase (Si)
17.2
 Atoms are mostly empty space
 Everything around us is mostly empty space…huh?
 We don’t fall into each other because your electrons repel
my electrons… like a magnet…we push off before we fall in
like a ghost!
 You know you never actually touch someone…WHAT??!
Craziness Cont. 17.2
 The repelling electrical fields create the feeling of
touch, but there is always a layer of electrons between
you and the other person.
17.3
 Protons are 2000 times larger than electrons, but have
the same charge
 The number of protons in an atom equals the atomic
number
 All elements have a different atomic number.

(elements fingerprint)
 Note: In an atom, the number of protons is equal to
the number of electrons.
Isotopes
 Isotopes
 atoms of the same element with a different mass
because of a different number of neutrons.
 The number of neutrons in an atom can change,
but the proton number will always remain the
same.
Designating Isotopes
There are two ways to designate isotopes:
 Hyphen notation
is when you write out the element name followed by a hyphen
and the mass #.
Calcium – 40
 Nuclear notation
is when the element symbol is written, then in the
upper left is the mass number.
40Ca
17.4 (Write this down, practice
tomorrow!)
# neutrons + # protons = mass number
# neutrons = mass number – atomic
number
17.5/17.6 - Periodic Table
 Vertical columns on a periodic table are called groups
or families. (label your table!)
 Horizontal rows on a periodic table are called periods.
The periods are numbered Period 1 to 7.
Metals vs. Nonmetals vs.
Metalloids
 Metals
 left side of the periodic table
 good conductors of heat and electricity
 malleable (can be hammered into sheets)
 ductile (rolled into wire)
Metals vs. Nonmetals vs.
Metalloids
 Nonmetals
 right side of the periodic table
 poor conductors of heat and electricity
 gases or brittle solids.
 Metalloids have properties of metals and
nonmetals.
Periodic Table
 Across the periodic table the properties of elements
gradually change – periodic trend
 Example: atoms get smaller as your move from the left
to the right
 Down the periodic table the elements properties are
very similar…hence the names “group or family”
Periodic Table Families
 Group 1 – Alkali Metals
 Group 2 – Alkaline Earth Metals
 Group 3-12 Transition Metals
 Group 16 – Chalcogens
 Group 17 – Halogens
 Group 18 – Noble Gases
 Alkaline Metals
 Middle ages, ash mixed with water….alkaline metals
 Alkaline Earth Metals
 Alkaline solutions in water, didn’t melt in fire “earth”
 Chalcogens
 “ore-forming” oxygen and sulfur common in ores
 Halogens
 “salt-forming” NaCl (table salt)
 Transition Metals
 Lanthanides (inner transition metals)..some used in
LED’s
 Actinides (inner transition metals)…nuclear power
industry, uranium and plutonium
Noble Gases
 The Noble Gases are group 18
 very stable
 do not like to react with anything
 Most of the Noble Gases are used in lighting, and
helium is used to inflate balloons so that they float.