Elements and CompoundsChemistry - 7th Grade | The Oxford School, Azuero

Prepared by Teacher Irina Ruiz

Monday, July 11, 2016

• The elements are arranged in order of increasing atomic number

• The horizontal rows are called periods• The vertical columns are called groups• Elements in the same group are similar to

each otherHydrogen is a non-metal but it is often put in the middle.

Notice that most elements are metals, rather than non-metals.

Each element has its own chemical symbol, made from letters. Remember that you will only find elements in the periodic table and never compounds.

1

2

3

4

5

6

7

Monday, July 11, 2016

METALSIron, magnesium and gold are examples of metal elements. Metals have properties in common. They are:

• shiny, especially when they are freshly cut• good conductors of heat and electricity• malleable (they can be bent and shaped

without breaking)Most metals also have other properties in common. They are:

• solid at room temperature, except mercury• hard and strong• they have a high density• they are sonorous

Monday, July 11, 2016

NON-METALSOxygen, carbon, sulfur and chlorine are examples of non-metal elements. Non-metals have properties in common. They are:

• dull (not shiny)• poor conductors of heat and electricity (they

are insulators)• weak and brittle (they easily break or shatter

when solid)Most non-metals also have these properties:

• they have a low density (they feel light for their size)

• They are NOT sonorous (they do not make a ringing sound when hit)

Monday, July 11, 2016

Compounds and Formulae!

Some atoms like to hangout with other atoms.

And others prefer to keep to themselves...

WATER MOLECULE FORMULA

H2O

When a group of atoms hang out together, it is called a MOLECULE !

WATER is a COMPOUND because their molecules are made of different kinds of atoms: 1 oxygen atom bonded with 2 hydrogen atoms

Monday, July 11, 2016

BASIC RULES ON NAMING COMPOUNDS

• If the compound contains a metal, the name of the metal comes first.

• If the compound contains a non-metal, the name of the non-metal is usually changed:

➡ When two elements form a compound the name often ends in ‘ide’

➡ When the third element is oxygen, the compound often have names ending with ’ate’

sodium chloride

A compound of Calcium, Carbon and Oxygen is called:

calcium carbonate

Monday, July 11, 2016

PREFIXES in CompoundsHow many of each kind of atoms are bonded together?

• ‘Mon’ or ‘mono’ means ONE

• ‘Di’ means TWO

• ‘Tri’ means THREE

carbon dioxide MOLECULE

carbon monoxide MOLECULE

Monday, July 11, 2016

When hydroxides are dissolved in water, they form solutions that can neutralise acids.

• NaOH sodium hydroxide

• KOH potassium hydroxide

• LiOH lithium hydroxide

Hydroxides are alkalis!

ACIDS ALKALIS

Monday, July 11, 2016

FORMULA NAME OF THE COMPOUND WHAT IS THIS COMPOUND MADE FROM?

H2O watertwo atoms of hydrogen

bonded with one atom of oxygen

NaBr sodium bromide

SO2 sulfur dioxide

CaCO3 calcium carbonate

MgSO4

KOHLiNO3

H2SMonday, July 11, 2016