Definitions Flashcards
Ph
A scale to measure how acidic or basic a liquid is. pH is a number from 0 to 14.
Indicator
An indicator is a dye or chemical that changes colour in the presence of an acid or base, and can therefore indicate or show whether a substance is an acid, base or neutral.
Periodicity or periodic table trends
Arranging elements according to their similar properties
Element
Is a pure substance that cannot be broken into smaller units or parts
Valency
The number of bonds formed by an atom of an element
Atoms
Consists of a small, dense nucleus in the centre and a nuclei consists of two types of particles, protons +, and neutrons (neutral)
Mass number
The number of protons and neutrons in a nucleus
Compound
A pure substance that consists of two or more elements that have chemically combined
Molecule
Defined as two or more atoms that have chemically bonded with each other in a fixed ratio
Diatomic molecule
Some non-metals (r.h.s of Periodic Table) are gases at room temperature that exist as molecules that are made up of two atoms each
Neutralisation reaction
When an acid and a base combine, they react together. This makes the acid less acidic but more neutral
Force
A push or pull of an object
Spring balance
A simple device consisting of a spring which when stretched gives a reading of the force used to stretch the spring
Free-body diagram
Using a circle to represent the object and the different length arrows to represent forces acting on the object
Contact force
Is exerted when two objects are in contact, that is, they touch each other
Friction
A contact force that a surface exerts on an object
Tension
Is a contact force in a rope/cable that is used to carry a load
Compression
Is contact force that squeezes/pushes something into a smaller space
Non-contact force
Or a field force, acts over a distance. The two bodies exert field forces on each other without touching each other
Weight/Fgravity
Any object that has mass experiences a gravitational force. Always exerted downwards towards the centre of the earth
Body mass
The measure of the amount of matter that it is made of
Magnetic force
A force that two magnetic objects exert on each other over a distance
Resultant/Net force
The single force that replaces all other forces. The sum of all the force acting on the object
Drag
Solid moving through a fluid substance; water, air etc.
Work
The process of transferring energy from one object/system to another/converting energy from one form to another
Work is done on an object
When a force acts upon an object to cause a displacement of the object in the direction of the force
Power
The rate at which work is done
Energy
The ability to do work
Kinetic energy
The energy an object possess due to its motion
Gravitational potential energy
The energy an object possesses due to its position above the ground
Mechanical energy
The energy that is possessed by an object due to its motion or its position
Electric current
Rate of flow of charge
Electron flow
Flow of negative charge from the negative to the positive terminal of a cell/battery
Conventional current
The flow of positive charge from the positive to the negative terminal of a cell/battery
Resistance
Opposition to the flow of charge
Short circuit
Happens when another, easier path is accidentally made in an electric circuit
Electromagnet
A coil of wire wrapped around a soft iron core connected to a power source
Electrolysis
A chemical reaction that takes place due to an electric current flowing through a conducting solution
Ammeter
Measuring device used to measure the electric current in the circuit
Voltmeter
Instrument used to measure potential difference
Potential difference
The work done per unit positive charge
Rheostat
An apparatus that varies resistance, increase/decrease current
Ohmic resistor
Obeys Ohm’s law where the ratio V/I is constant
Non-Ohmic resistor
One that does not obey Ohm’s Law and where the ratio V/I is not constant
Variable resistor
Resistors where we can adjust the resistance ourselves
Law of conservation of matter
Matter is neither created nor destroyed, so we must have the same number and kind of atoms after the chemical change as were present before the chemical change
Combustion
Process where some metals react with oxygen
Metal oxide
The product when metals are burnt in the air containing oxygen
Rust
A complex compound formed when iron in a metal reacts with oxygen
Galvanising
Process of applying a protective zinc coating to steel/iron to prevent rusting
Electroplating
Makes use of electrolysis, whereby an electric current is passed through an electrolyte and one metals deposited onto another
Sacrificial anode
Works by oxidising more quickly than the metal it is protecting
Non-metal oxide
Formed when you burn a non-metal in air, the non-metal reacts with the oxygen in the air
Decomposition
A reaction in which a compound splits up into two or more simpler substances. AB ➡️ A + B
Endothermic reaction
A reaction that the system absorbs energy from its surroundings in the from of heat
Exothermic reaction
A reaction that releases energy from the system in the form of heat
Electrolytic cell
When a solution of copper (II) chloride is placed in a beaker together with two carbon electrodes connected to a power source.
Synthesis reaction
The reverse of decomposition of a compound into elements. Elements that can react with each other to form a new substance - a compound
