properties of the periodic table families chemistry fall 2009
TRANSCRIPT
Properties of the Periodic Table
Families Chemistry Fall 2009
Octet Rule
Atoms tend to gain, lose, or share e- in order to get a full set of 8 valence e-
Useful for determining the type of ions likely to form
Elements on the right side of the periodic table tend to gain e-; forming negative ions
Elements on the left side of the periodic table tend to lose e- and form positive ions
Why do elements on the right side gain e – and elements on the left side lose e-?
Family 1A Alkali metals Easily lose a valence e-
and form a ion with a +1 charge
Soft enough to cut with a knife
Highly reactive – too reactive to be found free in nature; good conductors of heat and electricity Example: NaCl in salt
water
Family 1A - Lithium
Lightest alkali metal Found in water, soil,
and rocks Least reactive of alkali
metals Compounds of lithium
found in batteries and dehumidifiers
Used to strengthen glass and treat bipolar disorders
Hydrogen
Placed in 1A because it has 1 valence e-
H shares many properties with nonmetals and metals
Highly reactive http://www.open2.net/s
ciencetechnologynature/worldaroundus/akalimetals.html
Group 2A – Alkaline Earth Metals
Form compounds with oxygen called “oxides”
Shiny solids that are harder than alkali metals
Lose 2 valence e- to form ions with a 2+ charge
Calcium
Found widely in nature-rocks, coral reefs
Needed to maintain healthy teeth and bones
Decomposition of calcium carbonate forms lime – used to manufacture steel, paper, and glass.
Magnesium
Abundant Can be formed into any
shape Alloys are strong and
lightweight
Group 3A – The Boron Family
Found in nature combined with other elements
B, Al, Ga lose 3 e- to form ions with a +3 charge
Thallium loses only the p valence e- to form ions with a 1+ charge
Boron
Borax comes from California’s Mojave Desert
Cleaning agent and fireproof insulation
Boric acid used as disinfectant and eyewash
Boron nitride – 2nd hardest known material
Super abrasives
Aluminum
Most abundant metal in earth’s crust
Recycling aluminum is energy efficient compared to extracting it from its ore
Widely used – alum in antiperspirants and aluminum oxide in many gems
Group 4A – The Carbon Group
Carbon Can form many
different compounds Diamonds are hard,
graphite is soft – allotrope
C atoms in graphite share e- with other C atoms to form layers that slide
C atoms share e- with other C atoms in diamonds to form a 3-D solid
Silicon Computer chips and
solar cells Can be found in quartz
crystal, sand, and glass
Family 5A – The Nitrogen Group
Nitrogen
Abundant in the atmosphere
Proteins contain N Bacteria in soil convert
N from the atmosphere to nitrogen compounds that are easier to use by organisms
Ammonia – colorless gas, irritating odor
Phosphorus
Phosphate compounds can be found in cheese, laxatives, baking powders, flame-retardant fabric, grease remover in cleaning products
Essential for plant growth (fertilizers) – can be harmful to the environment
Bismuth
A compound of Bismuth is an active ingredient in a remedy for nausea and diarrhea
Group 6A – The Oxygen Group
Oxygen
6 valence e-; tend to gain two e- to form ions with a 2- charge; can also share 2e-
Ozone - unstable gas Most abundant element
in Earth’s crust Forms compounds with
every element except He, Ne, and Ar
Sulfur
Used to make acids to be used in fertilizers, steel, paper, and paints
Hydrogen sulfide used as an energy source in the ocean
Hydrogen sulfide released from volcanoes
Tarnish silver
Selenium
Supplements Found in eggs, fish,
and grains. Works with vitamin E to
prevent cell damage Used in solar cells -
converts light into electricity
Locoweed – toxic levels to grazing animals
copiers
Group 7A – The Halogens
Fluorine
Form compounds with almost all metals
Form ions with a 1- charge
Added to toothpaste and drinking water to protect tooth enamel from decay
Nonstick coating for cookware
Chlorine
Highly reactive Deadly gas Compounds of chlorine
are used as bleaching agents, stain removal
Cl compounds are used by dentists and hydrochloric acid is used to digest food, rust removal, plastic production
Iodine
Body needs iodine to maintain a healthy thyroid gland
Seafood and iodized salt are excellent sources of iodine
Kills bacteria – used by campers to disinfect water
Group 8A – Noble Gases
Helium
odorless and unreactive
Stable Sun Lightest noble gas Used in blimps,
airships, and balloons
Neon
Light displays High-voltage electricity
passes through the neon gas stored in a gas discharge tube, e- in the atoms become excited
E- return to a lower energy state and emit bright light