Year 10 Chemistry Revision Flashcards ionicons-v5-c

Element

A substance in its purest form. All the atoms are the same.

Molecules

Two or more atoms joined together. There atoms may be the same or they may be different.

Compound

Two or more different atoms joined together a set ratio

Atom

Smallest particle of matter with a set composition

Ion

An atom that has lost or gained an electron and has an overall charge

Isotope

A variation of an element. These have the same number of protons but can have a different number of neutrons.

A Physical Change

Is a reversible and involves a change in state. For example: Solid --> Liquid (ice -> water) Solid --> Gas (dry ice -> CO2 gas)The molecular structure does not change

A Chemical Change

Is accompanied by one or more of the following:colour changefizzing/gas given offodor given offtemperatureA new compound is formed with different characteristics and appearance to the reactions. This is irreversible. For example: Sodium in Water

Alkali Metals

Group one of the periodic table. They react with water to form alkaline solutions. They form +1 ions and are very reactive. They must be stored under oil. The are low in density, conduct electricity, are malleable and are shiny.

Alkaline Earth Metals

Group two of the periodic table. They are extracted from oxides on the Earth's crust. They are less reactive that group one. They form +2 ions, conduct electricity, are malleable and shiny.

Halogens

Group seven of the periodic table and are very reactive. They don't occur free in nature but as diatomic molecules. They combine with metals to form ionic salts. The states at room temperature change from gaseous to solid as you go down the group.

Noble Gases

Group eight of the periodic table. These are very stable and unreactive as they have eight electrons in their valence shell. They are the rare gases in the atmosphere.

Number of electrons in each energy level (shell)

Shell 1: 2 electronsShell 2: 8 electronsShell 3: 8 electronsShell 4: 18 electronsShell 5: 32 electronsShell 6: 50 electrons

Period

Each new _______ has a new electron shell

Group

Each new ______ has the same number of electrons in its outer shell. This is called the valence shell or valence electrons.

Valency

Refers to the number of electrons in the outer shell and the type of ion it forms.

Group 2

All have 2 electrons in the outer shell i.e. 2 valence electrons. When reacting they give these two electrons away to form ions with a 2+ charge

Group 3

All have 3 electrons in the outer shell i.e. 3 valency electrons. when reacting they give these three electron away to form ions with a 3+ charge

Group 4

All have 4 electrons in the outer shell. These elements are versatile in that they can either gain four electrons in a reaction or lose four electrons to get a full shell.

Group 5

All have 5 electrons in the outer shell. They want a total of eight so they need to gain three in a reaction. When they gain 3 electrons they form ions with a 3- charge.

Metals

These give away electrons.

Non-metals

These gain electrons.

Combustion

A reaction which occurs when oxygen combine with another compound to form water and carbon dioxide. These reactions are exothermic, mean that produce heat. Eg. C10H8 + 12 O2 ---> 10 CO2 + 4 H2O

Synthesis or Combination

A reaction which occurs when two or more simple compounds combine to form a more complicated one. These reactions come in the general form of A+B --> AB

Decomposition

A reaction which is the opposite of a synthesis reaction - a complex molecule breaks down to make simpler ones. These reactions come in the general form of AB --> A+B

Single Displacement

This is when one element trade places with another element in a compound. These reactions come in the general form of A+BC --> AC+B

Double Displacement or Precipitation

This is when the anions and the cations of two different molecules switch place, forming two entirely different compounds. These reactions are in the general rule of AB+CD --> AD+BC

Acid - Base

This is a special kind of double displacement reaction that takes place when acid and base react with each other. The H+ ion in the acid reacts with the OH- ion in the base, causing the formation of water. Generally, the product of this reaction is some ionic salt and water.

Ionic Compound

These form when a metallic atom gives one or more electrons to a non-metallic atom. These are often called a salt as it forms crystals.

Covalent Compounds

These are formed by a non-metallic ion sharing its electrons with another non-metallic ion.

Variable

A factor that can be changes and can affect the outcome (results) of an experiment. In a fair test we keep all variables the same except for the thing we are testing.

Independent Variable

The factor that is not changed by experimental conditions

Dependent Variable

The factor that we are measuring in the experiment.

Matter

This cannot be created or destroyed, it just changes form