Where it all is

John Newlands determined a repeating pattern of every 8 elements. He called it the law of octaves.

Developed in the 1860’s Dmitri Mendeleev arranged the first on

based on Atomic Masses. Henry Moseley Arranged the Modern

Periodic Table based on Atomic Number.

Based on increasing atomic number and on electron configurations◦ Results in repeating chemical and physical

properties. Groups or Families

◦ Columns that go up and down.◦ There are 18 Groups

Periods◦ Rows that go across◦ There are 7 Periods

Classification of ElementsMetals

◦ On the left side◦ Make up ¾ of all elements◦ Malleable, Ductile, Conduct electricity, form

positive ions. NonMetals

◦ On the Right side◦ Dull, Brittle, Insulators, form negative ions

Metalloids (Semimetals)◦ Found along the staircase between metals and

nonmetals, have properties of both.

Highly reactive Replace Hydrogen in Water All have 1 valence electron All are s1

Forms +1 ions

Very reactive Don’t replace Hydrogen in Water

◦ Readily burn in O2 when exposed to heat Calcium makes up your bones. Batteries get their name from this group Have 2 Valence electrons

◦ All are s2 – forms +2 ions

These are the common metals All have d orbitals filling Less reactive then other metals Copper, Silver, and Gold least reactive Forms various positive ions

Have 3 Valence electrons◦ All are s2 p1

◦ All form +3 ions except Boron which forms a –3 ion

One is a metalloid (Boron) The rest are all metals

Carbon family has 4 valence electrons All are s2 p2

Composed of:◦ one non-metal (Carbon)◦ Two metaloids (Silicon and Germanium◦ Two metals (Tin and Lead)

Carbon always forms 4 bonds◦ All known life based on Carbon

Computers function based on Silicon and Germanium’s unique properties◦ They conduct electricity but not heat

Lead and Tin are common metals◦ Used to be used a lot in food storage

All have 5 valence electrons◦ All are s2 p3

Composed of:◦ two nonmetals - Nitrogen and Phosphorous◦ Two metalloids – Arsenic and Antimony◦ One metal - Bismuth

Nitrogen:◦ makes up most of the atmosphere◦ Critical to plant and animal life◦ Forms strong bonds that are used in explosives

Phosphorous◦ Critical to plant and animal life

All have 6 valence electrons◦ All are s2 p4◦ Usually form 2 bonds

Form – 2 ions (except Polonium +2, +4 ions) Composed of:

◦ 3 nonmetals – Oxygen, Sulfur, Selenium◦ 1 metalloid – Tellerium◦ 1 metal - Polonium

All have 7 valence electrons◦ All are s2 p5◦ Forms 1 bond

Forms – 1 ions All are nonmetals Highly reactive

◦ Never found in nature as single atoms◦ When pure will form F2, Cl2, Br2, I2

All have 8 valence electrons◦ All are s2 p6◦ Rarely form bonds

Never form ions◦ Helium, Neon, Argon have never been found in a

compound◦ Krypton, Xenon, Radium can sometimes be forced

to form compounds – but these are very unstable

Called Rare Earths◦ They are rare on earth - Most are manmade

All are radioactive All elements greater then Uranium (92) are

manmade Some are used in medical research

TRENDS Atomic Radius – The size of the atom.

◦ Hard to measure due to cloud not being distinct◦ Smaller Up and Right◦ Negative Ions Larger◦ Positive Ions Smaller

Ionization Energy – The energy required to remove one electron, the more electrons removed, the more energy required.◦ Greater Up and Right◦ Fluorine the highest ◦ Francium the lowest

More on Trends Electronegativity – The ability of atoms to

attract electrons during bonding◦ Greater Up and Right◦ Fluorine the Greatest Electronegivity◦ Francium the Lowest

Octet Rule – Atoms Tend to gain, lose or share electrons to have a full (s2, p6) valence shell.

Shielding Effect – The ability of inner electrons to shield valence electrons from the nucleus. Increase Down, Across Same