Chemistry Part 2 Yr9/10 Revision

What is an atom?

Basic building blocks of matter made up of 3 sub-atomic particles protons (pos) neutrons (neutral) and electrons (neg). Protons and neutrons are in the nucleus of an atoms and electrons are much smaller moving fast around the nucleus in shells, which form an electron cloud around the nucleus.

What is an atomic no?

Protons

What is a mass no?

Protons and neutrons

What is an element?

substance made up of only one type of atom.

Allotropes?

Pure form of an element in different ways.
e.g carbon can be a Dimond or graphite

Isotopes?

Isotopes aredifferent forms of the same chemical element. They have the same number of protons, but a different number of neutrons in their nucleus. This means they share the same atomic number but have different mass numbers

Periods?

Horizontal rows telling the number of electron shells in an atom

Groups?

Vertical columns showing number of valence electrons in an atom

Electron shells?

(2,8,18,32) last 2 are happy with 8 though

Molecules?

Groups of two or more atoms that are bound together

Compound?

Substance formed from more than one element

Properties of metals

LEFT HAND SIDE OF PT
good conductors of heat and electricity
lustrous
malleable
ductile
high denisty

Non metals properties

RIGHT HAND SIDE
good insulators of heat and electricity
low melting and boiling points
brittle
dull

Metalloids properties

good insulators
brittle
dull

Ions

An ion is an atom or molecule that has a net electrical charge. This happens because the number of positive protons does not equal the number of negative electrons.
If an ion looses an electron it becomes more positively charged and is a cation
If an ion gains an electron it becomes less positively charge and is an anion.

Groups in the PT and their properties

Alkali Metals: reactive
Alkali Earth Metals: Reactive, Soft, Brittle
Transition metals: strong, shiny, malleable, ductile, conducts heat and electricity.
Post-transition metals: low reactivity, low melting point and soft
Metalloids: combination of properties, semi conductor heat and electricity
Halogens: Reactive, non metal, brittle, low melting point and boiling point and is a good insulator
Noble Gasses: non- metal, very unreactive and don’t form ions

What is chemical bonding?

atoms bond to form a molecule or a lattice. In g18 they do not bond as they have a full outer shell.
There is metallic, ionic and covalent bonding.

Metallic bonding

Metal plus metal
Metallic bonding is the attractive force between positive metal ions and a shared "sea" of free, delocalized valence electrons. This "electron sea" model holds metal atoms tightly in a regular crystal lattice structure, giving metals their unique physical traits

Ionic bonding

metal plus non metal
a type of chemical link that forms when one atom gives one or more electrons to another atom. This electron transfer creates charged particles called ions, which stick together because opposite electrical charges pull on each other.

Covalent bonding

Non-metal plus non metal
Covalent bonding is a chemical link where two atoms share pairs of valence electrons. This sharing helps each atom reach a stable, full outer electron shell. It usually happens between nonmetal atoms that have similar pull or attraction for electrons

What is an acid reaction?

acid reaction is a chemical process where a substance with a pH below 7 (an acid) gives away hydrogen ions to another substance

What is an acid?

produces pos H atoms when dissolved in water pH below 7

What is a base?

react with an acid to neutralize it pH above 7

Acid + metal

= salt and hydrogen

Acid + base

salt + water

Acid + carbonate

salt + water + carbon dioxide

What is a pH scale?

measures the concertation of H pos in a solution
Acidic= less than 7
Netral= 7
Basic= more than 7

Stronger acids vs weakers

Strong acids lose their H+ very easily and are corrosive. Weaker acids lose only a few H+ ions (not very easily)