8th Grade Science-Periodic TableProperties of the Periodic Table

The Periodic Table

• Dimitri Mendeleev-arranged all the elements known in order of increasing atomic masses and discovered a pattern

• Today’s Periodic Table—elements are arranged by increasing atomic number and by changes in physical and chemical properties

• Mendeleev-left blank spaces to keep elements in line according to chemical properties

• He predicted the existence of two elements not yet discovered

Groups

• The vertical columns in the periodic table-also called families

• Elements in groups have similar properties

• Periodic Table—pg. 128 and 129 in textbook

*Elements in the same group have the same number of valence electrons

*This means these elements will all bond similarly

Periods/Rows• Horizontal groups

across the periodic table

• Each row ends with an element with a full outer valence (8 electrons)

• Periods increase by one proton and one electron going L to R

• Many other properties of elements increase either left to right or right to left across the periodic table as well.

• Ex: electronegativity, atomic radii, etc.

Metals

• Metals are on the left-hand side of the periodic table

• Most are shiny, ductile, malleable and are good conductors

• Ductile—drawn into wire• Malleable-can be

hammered into sheets

Non-metals

• Non-metals are on the right side of the periodic table

• Most are gases, brittle, are poor conductors, and are solids at room temperature

Metalloids

• Metalloids-run along the middle zig-zag line

• Metalloids have some of the properties of both metals and non-metals

Metalloids

• Are considered semiconductors—can conduct electricity better than nonmetals, but not as well as metals

• *Review pg. 135 of book

Groups of the Periodic Table

• Group 1—Alkali Metals• All have 1 valence

electron and are highly reactive

• Group 2—Alkaline Earth Metals

• All have 2 valence electrons and are reactive, but not quite as reactive as Group 1

• Groups 3-12*Called the “Transition

Elements” because they are in transition between Groups 1 and 2 and Groups 13-18

*They have no specific number of valence electrons per group

Group 13 elements-Boron Group• All have 3 valence

electrons• Boron-metalloid-common

in some household products-borax, boric acid

• Aluminum-most abundant metal in Earth’s crust

• (cans, foil, pans, siding)

Group 14 elements-Carbon Group• Carbon-silicon, nonmetal,

silicon and germanium are metalloids, and tin and lead are metals

• Carbon occurs as an element in coal, oil, natural gas, foods

• All Group 14 elements have 4 valence electrons

Group 15 Elements-Nitrogen Group• All have 5 valence electrons• Tend to share electrons when

bonding• Ex: ammonia, fertilizer,

nitrates• Phosphorus-water softeners,

fertilizers, match heads, china• Antimony and Bismuth-low

melting points/mixed w/other metals

Group 16 –Oxygen Group

• All have 6 valence electrons

• Exists in air as a diatomic molecule

• Ozone-protects us from sun’s radiation

• Sulfur-nonmetal, exists in different forms, used as pigment in paint

Group 17 Elements-Halogens

• All have 7 valence electrons, so very reactive

• Form compounds that have many uses-toothpaste, disinfectants, etc.

• Form salts when they bond with other elements

Group 18 Elements-Noble Gases• Have 8 valence electrons• Satisfy the “octet rule” • Are very stable and do

not bond with other atoms in nature

• *used for neon signs, lighting, balloons, etc.

Lanthanide and Actinide Series• Located at bottom of

periodic table• Separated from rest of

periodic table to keep other elements in order

• Most are man-made elements

Synthetic Elements

• Scientists break apart elements in order to make new SYNTHETIC elements

• Synthetic elements on the periodic table are those with an atomic # greater than 92

• CHNOPS-Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur

• These are the most abundant elements in living organisms

Diatomic Elements

• These elements exist naturally as diatomic elements (2 atoms bonded together)

• Hydrogen Iodine• Nitrogen Chlorine• Fluorine Bromine• Oxygen• Acronym: Have No Fear

of Ice Cold Beverages

Periodic Table websites:

• www.chemicool.com• www.Ptable.com• www.periodictable.com• www.webelement.com