Chem test periodic trends

Hydrogen

•  Group 1, period 1

• Gas at room temperature

Alkali Metals

• Group 1, under Hydrogen

• Have one valence electron

• shiny, consistency of clay, can be easily cut

• most reactive

• react violently with water

• never found naturally

• always bonded

Alkaline Earth Metals

• Group 2

• never found uncombined in nature

• have 2 valence electrons

• react with water; forms hydrogen bases and gas

• less reactive than Alkali Metals

Transition metals

• Group 3-12

• Has Mercury, only one that is liquid at room temp

• often paint pigmints

• have 1-2 valence electrons, lose them when bond is formed with other atoms

• many combine chemically with oxygen to create compounds called oxides

Boron Family

• Group 13

• Named after first element in family

• B is only metalloid, rest are metals

• contains most abundant metal in earth’s crust: Aluminum

Carbon Family

• Have four valence electrons

• Includes non-metal (C), Metalloids, and Metals

• C is “basis unit of life”

Nitrogen family

• N makes up 78% of earth’s atmosphere

• nonmetals, Metalloids, metals

• 5 valence electrons

• share electrons when bond

Oxygen family

• Six valence electrons

• Most share electrons when forming compounds

• O is most abundant element in earth’s crust

• O combines with almost all metals 

Halogen Family

• Seven valence electrons, most reactive nonmetals

• never found free in nature

• need 1 electron to fill outer shell

• react with alkali metals to form salt

Noble Gases

• colorless gasses

• extremely unreactive

• Inactive because outer shell is full

• Inert, do not form compounds

• all are found in small amounts naturally

• 8 valence electrons

Rare Earth Metals

• Bottom of periodic table

• most are synthetic and manmade 

What do you notice about number of energy shells and periods?

Amount of energy shells is equal to the group its in

Why is Hydrogen so difficult to place?

Has only 1 valence electron

What trend do you notice with the number of valence electrons?

Valence electrons are same as group #

Trend from left to right across a period

Increase by one from left to right

How do you figure how many valence electrons an atom of an element will have?

The group

What is an isotope and an example?

An atom of an element with same # of protons but different number of electrons

Example: Carbon

Mendeleev

created earliest version of periodic table

Noticed when elements were arranged by increasing atomic mass, chemical properties were repeated periodically

Arastotle

Original four elements: Earth, water, fire, air