The Periodic Table of the Elements

Looking for Patterns

• Matter is made of about 100 different elements. (118 to be exact)

• Some are very reactive; some are not.

• 1800s - scientists began to suspect elements could be organized in a useful way.

Dmitri Mendeleev

• (1869) – Mendeleev discovered a hidden pattern.

• Similar chemical & physical properties.

• Atomic Mass (how heavy they are)

• Bonding Power - # of chemical bonds an element can form

(he studied reaction with oxygen)

The first periodic table• Mendeleev liked to play

Patience, a solitaire game.

• Pattern – elements arranged in order of increasing atomic mass

• Bonding Power – orderly pattern across rows

• Each column had similar properties in its own group

• Periodic means regular, repeating pattern.

Groups & Families

• An elements properties can be predicted from its location in the table.

• Table is arranged by 18 columns & 7 rows. • Columns are called groups or families. • Groups have similar characteristics. • Every family member has the same number of

valence electrons

Rows & Periods• Each row is called a period. • The number of valence electrons increase across periods. • Reactivity decreases a from left to right (metals) • Reactivity increases left to right (non-metals)• Noble gases are stable

MetalsMetals are:

1.Great conductors - can transfer heat and electricity), shiny,

2.Ductile – can make into wire.

3.Malleable (easily shaped).

4.Shiny and has high density.

Alkali metals

• Group 1 (Li, Na, K, Rb, Cs, Fr)• VERY REACTIVE!! • Only 1 valence electron• They are not found in

element form (usually in compound form).

• Soft & Shiny• They tend to donate their

electron

Alkaline Earth Metals• Group 2: Be, Mg, Ca,

Sr, Ba, Ra. • Not as reactive, but

good enough! • Not found uncombined

in nature. • 2 valence electrons.• Hard, gray-white, good

conductor.

Look! It’s Beryllium Man!!!

Barium Esophagram

Transition Elements • Groups 3-12. • Bridge the reactive metals with less reactive elements. • Fe, Cu, Ag, and Au are good examples• Fairly stable! • Reacts slowly if at all. • Transitions give electrons (but have different bonding rules)

Examples of Transition Metals

Lanthanides

• Fits into period 6.

• Soft, malleable, shiny, high conductivity.

• Used to make alloys (mixtures of metals)

Actinides

• Fits into Period 7 (#58-#103)• Uranium and Plutonium are

examples. • All are radioactive! (unstable)? • E.g. Americium – used in smoke

detectors.

Non-metals• There are 16 non-metals each located to

the right of the zigzag line in the periodic table. (17 total)

• Very important for LIFE to exist! (CHNOPS)!

Non-metals properties• Many are gases at room temperature. • Some are solids. • Only one is a liquid. • Bad conductors, but good insulators, dull, can’t bend or shape them

like metals. • Big Idea!!!! – PROPERTIES OF NON-METALS ARE OPPOSITE TO

THOSE THAT CHARACTERIZE THE METALS.

Non-metals – The families

• Boron Family Group 13 & has 3 valence electrons• Carbon Family Group 14 & has 4 valence electrons• Nitrogen Family Group 15 & has 5 valence

electrons• Oxygen Family Group 16 & has 6 valence electrons• The Halogens Group 17 & has 7 valence electrons • The Noble Gases Group 18 & has 8 valence

electrons

What about Hydrogen????

• All alone in upper left-hand corner of periodic table. • Simple element. • Non-metal (but has one valence electron).• Every 90% of atoms in universe made of hydrogen. • Combines well with oxygen (H2O)

The Hindenberg – 1937 ↓

Finally, Metalloids(Also called semimetals)

• On the border between metals & non-metals. Shares characteristics.

• Most common is Silicon (Si). • Varies on how it conducts electricity (depends on temperature,

light, humidity, etc.) • Silicone & Germanium are used to make semiconductors.

Semiconductors

• Under some conditions carry electricity.

Used to make:

• Computer chips

• Transistor

• Lasers