Science Flashcards
What is a unit
A physical quantity we can use when measuring
Some examples include force (N), moment (NM) and density (KG/m^3)
What is an si unit
A quantity that is defined in terms of base or other derived quantities must then be a derived quantity.
They are all used in experiments
List some examples of si units
Mass(KG), length (M), Time(s), Moles (mol), Current(A), temperature (K or c) and luminosity (cd)
What is a scalar quantity
A quantity with magnitude only
What is a vector quantity
A quantity with direction and mahnitude
What are Cartesian coordinates
A coordinate relative to the fixed reference point( the origin)
How does a fact differ from an opinion
A fact can be proven but an opinion is debatable
What is science
The use of evidence to construct testable explanations and predictions
What are the six steps of a scientific method
1.observation
2.question
3.hypothesis
4.experiment
5.conclusion
6.result
What did John dalton discover
1803 - All matter is made of atoms
“Atoms cannot be broken into anything smaller”
What did JJ Thompson discover
1897 - the electron and the plum pudding model
What did earnest Rutherford discover
1910 - the alpha scattering experiment showed:
1) the model was mostly empty space ( most passed through
2)the nucleus was positively charged (some slightly deflected)
3) most mass in the middle (a few bounce back)
What did Neil’s Bohr discover
He theorised that the electrons orbit at set distances with specific amounts of energy and that they can switch energy levels by absorbing or emitting electro-magnetic radiation
What did James Chadwick discover
1912 - The neutron
What is an atom
A small particle that makes up all objects
What is a element
A substance made of one atom/molecule. These are all on the periodic table
What is a compound
A mixture of 2 or more elements chemically bonded
What is a mixture
A blend of elements and/or compounds that aren’t chemically bonded
What is valency
Describes how easily an atom or radical can combine with another chemical species. This is determined by the number of electrons gained, lost or shared if it reacts with another atom
Essentially it is the bonding of atoms to gain full outer shells
What is an ion
Any atom or group of atoms that bear one or more + or - charges
+ = cations
- = anions
What is electronic structure
Also known as electronic configuration, it is how the electrons arrange themselves in shells
What is covalent bonding
Shared electrons between 2 non-metals
What are small molecules
Contains a few bonded atoms
Eg methane, ammonia, chlorine molecule
What are Giant structures
Millions of atoms that are joined together
Eg graphite, diamond, silicon dioxide
What is metallic bonding
Metal and metal with sea of delocalised electrons which can carry a charge
What are the properties of a pure metal
Soft, arranged in layers that slide over each other which makes them malleable
What is an alloy
A mixture of different metals which often gives high melting points, good conductivity of electricity and thermal energy and malleability
What is a soluble
A substance that can dissolve in a liquid
What is a solute
A solid that cannot dissolve
What is insoluble
A substance that cannot dissolve in a liquid
What is a solution
What is made when a solid dissolves into a liquid
What is the solvent
The liquid that the solid dissolved into
What does a reaction between metal and acid create
METAL + ACID -> SALT + HYDROGEN
What test is used for hydrogen
The squeaky pop test
What is chemical etching
A process that changes the texture of a surface with alter roughness and increase bonding effectiveness and can make it facilitate retention of oils or the opposite
What is electrolysis
The process by which ionic substances in a compound become disassociated when an electrical current is passed through it
What is the process of electrolysis
When a soluble ionic compound dissolves in water the lattice breaks up. The ions separate and are free to move. They can carry electrical charge through the solution making it conduct electricity
What is disassociation
A reversible process of separation of charged particles in a compound. It involves separating metal from ore
What is anodising
An electrolytic passivation process used to increase the thickness of oxide layer on the surface of a metal
What is electro plating
Application of electrolytic cells in which a thin layer of metal is deposited onto an electrically conductive surface. The electrodes of a cell are held apart from one another
What are galvanic protection
A way to protect iron or steel from rusting by applying a zinc coating as a sacrificial anode
What is a cell
A chemical energy store. They transfer chemical energy to electrical by a chemical reaction
What is an electrode
The metal in a battery
What is newtons 1st law?
If the forces acting on an object are balanced the it will be at rest or move at a constant speed if it’s moving
What is a lever
A simple pivot machine that acts as a force multiplier
What is a moment
The applied force produces a turning effect called a moment when acting on a pivot point.
What is the principal of moments
For a lever to be balanced the sun of the clockwise moments must equal the sim of the anti-clockwise moments
What is a torque
A moment that causes rotation about an axis
What conditions are necessary for equilibrium
1) the net external force is zero
2) the net external torque is zero
