Definitions Flashcards
What is a mixture
A combination of two or more substances where the substances are not joined or bonded together and no chemical reaction occurs between the substances
What is an element
A substance that cannot be broken down into other substances by chemical means
What is a compound
A group of two or more atoms, attracted by a relatively strong bond, the atoms are combined in fixed proportions
What is a cation
A positive ion formed when a neutral atom loses one or more electrons
What is an anion
A negative ion formed when a neutral atom gains one or more electrons
What is a metalloid
A element with mostly non-metallic properties, their distinguishing characteristic is that their conductivity increases as their temperature increases
What is diffusion
The movement of particles from a high concentration to a low concentration
What is the Brownian motion
Random motion of particles suspended in a liquid or gas resulting from their collision with quick atoms or molecule in the liquid or gas
What is a freezing point
The temperature at which a liquid changes it’s phase to become a solid
What is a boiling point
The point at which a liquids vapour pressure is equal to atmospheric pressure
What is a melting point
The point at which a solid changes it’s phase to become a liquid
What is evaporation
Process of going from a liquid to a gas
What is sublimination
Process of going from a solid to a gas
What is condensation
The process of going from a gas to a liquid
What is the kinetic molecular theory
All matter is composed of particles which have a certain amount of energy which allows them to move at different speeds depending on the temperature (energy)
. There are spaces between the particles and also attractive forced between particles when they come closer together.
What is latent/transitional heat
The heat produced or released during a phase change
What are volatile liquids
Liquids that evaporate at room temperature
What is the difference between macroscopic and microscopic properties
Macroscopic properties refer to boiling and melting melting points and evaporation. Microscopic refers to what happens in the atom and the molecular structure of sun stances
What is Relative atomic mass
The ratio of the average mass of one atom of an element to one twelfth of the mass of atom carbon-12
What is atomic number (Z)
Number of protons in an atoms
What is a proton
A particle found in the nucleus of an atom, it is positively charged
What is an electron
Smallest particle that makes up an atom and is found outside the nucleus, it is negatively charged
What is a neutron
A particle found in the nucleus of an atom, it has no electrical charge
What is atomic mass (A)
Number of protons and neutrons in the nucleus of an atom
What is an isotope
Atoms of the same element that have the same number of protons (Z), but a different number of neutrons (A) resulting in different atomic masses.
What is the Aufbau Principle
Electrons orbiting one or more atoms, fill the lowest available energy levels before filling their higher energy levels.
What is Hunds rule
Electrons would rather be in a subshell on their own than share the orbital in the same energy level
What is Pauli’s Exculsion principle
Electrons have a property spin and two electrons must have opposite spin in order to share a subshell
What is an orbital
Region of space where you are most likely to find electrons
What are valence electrons
Electrons that are found int the outermost energy level of an atom that can participate in forming chemical bonds with other atoms
What is an atomic radius
The measure of size of the atom (the distance from the centre of the nucleus to the point where the electron cloud ends)
What is a group
Vertical columns on the period table
What is electron affinity
The amount of energy released when an atom in the gaseous phase gains an electron to form a negative ion
What is electronegativity
The measure of the tendency of an atom to attract bonding electrons
What is a chemical bond
A Physical process that causes atoms to be attracted to each other and held together in more stable compounds called molecules
What is the first ionisation energy
The amount of energy required to remove the first electron from an atom in its gaseous state to form a positive ion
What is periodicity
Quality or character of being repeated in intervals
What is valency
The number of electrons in the outer shell of an atom which are able to form bonds with other atoms
What is molar mass
The mass of one mole of that substance
What is a halide
A binary compound of a halogen with another elector group of elements
What is an oxide
An ion of oxygen (O2-)
What is ionic bonding
A transfer of electrons and subsequent electrostatic attraction
What is covalent Bonding
A sharing of at least one pair of electrons by two non-metals
What is metallic bonding
Electrostatic attraction between the positively charged atomic nuclei of metal atoms and a sea of delocalised electrons
What is a delocalised electron cloud
Electrons that are not at a specific point in a group of atoms
What is a molecule
When atoms share electrons, are bonded covalently then the resulting collection of atoms is known as a molecule
What is a covalent molecular structure
A crystal lattice that consists of separate molecules
What is a covalent network structure
Crystal lattice that consists of giant repeating lattices of covalently bonded atoms
Molecular formula
A concise way of expressing information about the atoms that make up a particular covalent molecular compound. Gives the exact number of each type of atom in the molecule
What is the empirical formulae
Shows the simplest ratio of atoms in the compound
What is physical change
A change that does not alter the chemical nature of the substances, no new chemical substances are formed
What is a chemical change
A change in which the chemical nature of the substances involved changes, new chemical substances are formed
What is the law of constant proportions
A chemical compound always contains exactly the same proportion of elements by mass
What is the law of conservation of mass
The total mass of substances taking part in a chemical reaction is conserved during the reaction
What is dissolving
Solid ionic crust and breaking up into ions in H2O
What is Dissociation
The process in which ionic compounds separate into smaller ions
What is hydration
Where ions become surrounded with water molecules in a water solution
What are electrolytes
A substance that contains free ions and behaves as an electrically conductive medium
What is a precipitate
A solid that forms in a solution during a chemical reaction
What is non polar covalent
The equal sharing of bonding electrons
What is polar covalent
The unequal sharing of bonding electrons
What is a frame of reference
A reference point combined with a set of directions
What is position
A vector quantity that points from the reference point as the origin
What is displacement
The change in position of an object
What is distance
The length of the path travelled
What is speed
The rate of change in distance
What is velocity
The rate of change in displacement
What is average speed
The total distance covered in the total time (eg you travelled from a to b to c what is the average speed from a to c)
What is instantaneous speed
Instantaneous speed is the speed at a particular moment in time
What is average velocity
The total displacement per unit time (total distance/ total time) (takes on the direction of the displacement.)
What is instantaneous velocity
The velocity at a particular moment in time
What is acceleration
The rate of change of velocity
What is gravitational potential energy
The energy an object poses due to its position relative to a reference point
What is gravitational potential energy
The energy an object poses due to its position relative to a reference point
What is Kinetic energy
The energy an object has as a result of the objects motions
What is mechanical energy
The sum of gravitational potential energy and kinetic energy at a point
What is the law of conservation of energy
The total energy in a system cannot be created or destroyed only transformed from one form to another
What is the principle of conservation of mechanical energy
On the absence of air resistance, friction or any external forces, the mechanical energy of an object is constant
(Ep + Ek)i = (Ep + Ek)f
What is amplitude
The maximum disturbance of a particle from rest/equilibrium position
What is constructive interference
When two pulses (waves) meet, resulting in a bigger pulse (wave)
What is destructive interference
When two pulses (waves) meet, resulting in a smaller pulse (wave)
What is a wave
A periodic , continuous disturbance that consists of a train of pulses
What is a transverse wave
A wave where the movement is perpendicular to the direction of the propagation of the wave. Succession of transverse pulses.
What is a longitudinal wave
A wave where the particles in the medium move parallel to the direction of the propagation of the wave. Succession of longitudinal pulses
What is rare fraction
A region in a longitudinal Wave where particles are furthest apart
What is a compression
A region in a longitudinal wave where the particles are closed together
What is wavelength
The distance between any two adjacent points that are in phase.
What is frequency
The number of successive crests (or troughs) passing a given point in one second
What is a period
The time taken for two successive crests (or troughs) to pass a fixed point
What is a crest of a wave
The point where the displacement of the medium is at its maximum
What is the trough of the wave
The point of the wave where the displacement of the medium is at its minimum
What is the wave speed
The distance travelled by the wave per unit time. Product frequency and wavelength of a wave. c = f λ
What is ultrasound
Sound with frequencies higher than 20kHz up to about 100kHz
What is electromagnetic radiation
Radiation consisting of self-sustaining oscillating electric and magnetic fields at right angles to each other and to the direction of propagation. It does not require supporting medium and travels through space at the speed of light
What is the dual nature of electro magnetic radiation
It behaves as a particle and a wave
What is a photon
A particle of light with a discrete amount of electromagnetic energy
What Is a magnetic field
A region of space where a magnet or ferromagnetic material will experience a non contact force
What is the gravitational field
The force acting per unit mass
What is gravitational potential energy
The energy an object possesses due to its position relative to a reference point
What is kinetic energy
The energy an object has as a result it’s motion
What is mechanical energy
The sum of gravitational potential energy and kinetic energy at a point
Activation energy
The minimum energy required to start a chemical reaction
