Periodic Table

Keywords:

  • Atoms

    • Smallest units that elements are made of (ten millions of a millimeter).

  • Molecule

    • When two or more non-metal atoms are chemically bonded together.

    • eg. H2, O2 and Cl2.

    • Compound eg. HO2 and CO2.

  • Salts

    • When a metal bonds with a non-metal.

    • eg. NaCl (sodium chloride) or Fe2O3 (iron oxide/rust).

  • Element

    • Pure substance.

    • Made up of only one type of atom that cannot be split up into simpler substances by chemical reactions.

    • There are 100 listed on the Periodic Table.

  • Compound

    • Is when two or more elements are chemically bonded together.

    • Their properties are nothing like the original elements.

    • The can be decomposed into their elements.

    • They can be molecules or salts.

Sub-Atomic Particles and Atomic Structure:

  • Atoms are made up of smaller particles called sub-atomic particles.

  • The nucleus is made of protons (p+) which are positively charged and neutrons (n0) which are neutral (ie. have no charge).

  • The mass number = p+ + n0

  • The nucleus is very tiny compared to the rest of the atom yet it contains more than 99% of the mass of the atom.

  • Electrons (e-) are negatively charged. They are arranged in energy levels around the nucleus like the layers of an onion. The first layer can contain 2 electrons, the next few can contain 8. These layers correspond with the periods on the Periodic Table.

  • Atoms are neutral therefore have an equal number of p+ and e- .

  • The atomic number is equal to the number of p+ (and e- in a neutral atom) which gives it its position on the periodic table.

Steps for Naming Compounds:

Steps:

  • Step 1:

    • Identify the elements in the compound.

  • Step 2:

    • Write down the name of the metal first.

  • Step 3:

    • If the compound contains only 2 elements, name the 2nd element and make it end in ‘-ide’.

  • Step 4:

    • If the compound contains 3 elements, one of which is oxygen, name 1st and 2nd elements and end in “-ate”.

Exceptions:

  • OH is called hydroxide.

  • When a metal is bonded with OH the compound’s name will end in

‘-ide’.

  • eg. NaOH = sodium hydroxide.

Prefixes:

  • Non-metal bonded to a non-metal.

    • 1 - mono.

    • 2 - di.

    • 3 - tri.

    • 4 - tetra.

  • eg.

    • CO - Carbon monoxide.

    • CO2 - Carbon dioxide.

    • CCl4 - Carbon tetrachloride.

Valence Electrons and Valency:

Valence Electrons:

  • The ratio which atoms bond depends on the valence of different elements.

  • Valence electrons: are number of electrons in the outermost shell that are involved in forming chemical bonds.

  • When bonding the element with more valence electrons takes the valence electrons from the element with less.

Binding Possibility (Valency):

  • Definition: The number of electrons an atom needs to gain, lose or share to be in a stable state (octet → 8 valence e-)

Transition Metals:

  • We use Roman numerals to indicate the valency of elements.

  • eg.

    • Zinc(II) Sulphide.

    • Iron(IV) Oxide.

Polytomic Ions:

Writing Symbols From Names:

Prefix Rule:

  • If it has a prefix, take it literally.

    • Carbon Dioxide ≠ CO4.

    • Carbon Dioxide = CO2.

Roman Numerals:

  • Roman numerals state the valency for transition metals.

Method: