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