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