Periodic Table

Dmitiri Mendeleev, 1871

• Listed the elements in columns in order of increasing atomic mass.

Henry moseley, 1913

• Determined the atomic number of the atoms of the elements.

• Arranged the elements in a table by atomic number.

• This is the way the periodic table is arranged today.

Metalsmetals metalloids nonmetals

Properties of Metals: •Luster•Ductile•Malleable•Good conductors of heat and electricity, •Lose electrons to form + ions

Metals

Non-metalsmetals metalloids nonmetals

•Nonmetals Properties: •dull•brittle•Insulators•(poor conductors) •gain electrons to form – ions

Non-metals

Noble GasesN

oble Gases

Noble Gasesare non-reactive, they have full electron shells

are periodic functions of the number of valence electrons an atom has.

Groups or families (vertical column) - have similar chemical properties.

Periods (horizontal rows) of elements usually start with a reactive solid and end with an unreactive gas, called a noble gas.

Valence Electrons:

• Electrons in the most outer ring of an element’s atom.

• Example: Group 1 all have one valence electron

3Periodic Table Trends

• Patterns caused by the valence electrons on the periodic table.

Atomic Radius

• The size of an atom

Electronegativity: the ability of an atom to attract electrons

Ionization Energy

Energy needed to remove one of atom’s electrons from its outermost shell

high ionization energies = Stronger hold on electrons

low ionization energies = weaker hold on electrons

Losing an electron is called ionization