Science Year 9 Flashcards
(29 cards)
What does an element contain
An element contains only one type of atom. All elements are given a symbol and are found in the periodic table
How is the periodic table arranged
The periodic table is arranged into groups (columns) and periods (rows),
What if elements are in the same group
They will have the same amount of electrons in their outer shell
And have similar properties
What are compounds
Compounds are 2 or more elements that are chemically bonded
are made in chemical reactions
Compounds are given a formula for example carbon dioxide is CO2 means 1 carbon atom and 2 oxygen
atoms
Another example is calcium hydroxide Ca(OH)2 which means 1 calcium, 2 oxygen atoms and 2 hydrogen atoms
What happens in some chemical reactions
In some chemical reactions it may appear that there are less products then there were reactions; however this is often because a gas has been made and this has escaped into the atmosphere
What is a conservation of mass
In a chemical reaction, chemcial bonds are broken the atoms are rearranged and the chemical bonds are made again
In a chemical reaction, (mass is never lost), you must start and finish with the same mass
What is an element
A substance that contains only one type of atom
What is a mixture
A mixture is two or more different atoms which are not chemically boned - can be separated
What is a compound
Two or more elements that are chemically boned
What is a group
The columns on the periodic table
What is a period
The rows on the periodic table
What is a reactant
What you start with in a chemical reaction
What is a product
What is made in a chemical reaction
How do we balance equations
We need to write balanced chemical equations represent chemical reactions and the convections of mass
Write down a balanced equation
2H2 + O2 - 2H2O
What does pure mean
A substance made of only ONE type of element or compound
What does impure mean
A mixture of elements and/or compounds
What does chromatography mean
A technique where mixtures can be separated based on their solubility
What does distillation mean
A separation technique which means a mixture of two liquids is heated
What does crystallisation mean
Method of mixture separation where a solvent is evaporated, leaving the solute behind
What is an atom
The particles that make up all substances with mass, they contain protons, neutrons and electrons
What is a nucleus
The centre of an atom, it contains protons and neutrons
What is a Nanometre
A unit measurement: 1x10-9 m
What is a proton
A sub atomic particle found in the nucleus, it has a charge of +1 and a relative mass of 1
