chemistry definitions (10) Flashcards
cation
a positive ion formed when a neutral atom has lost one or more electrons
anion
a negative ion formed when a neutral atom has gained one or more electrons
diffusion
the movement of particles in a high concentration to a low concentration
freezing point
the temperature at which a liquid changes it’s phase to become a solid
boiling point
the temperature at which vapour pressure of a substance equals atmospheric pressure
melting point
the temperature at which a solid changes it’s phase or state to become a liquid
evaporation
process of going from liquid to gas
sublimation
process of going from solid to gas
condensation
process of going from gas to liquid
relative atomic mass
the ratio of the average mass of one atom of an element to one twelfth if the mass of an atom of carbon-12
mass number
number of protons and neutrons in the nucleus of an atom
isotope
are atoms of the same element that have the same number of protons but a different number of neutrons resulting in different atomic masses
orbital
region of space where you are most likely to find electrons
atomic radius
the measure of the size of an atom ie the distance from the centre of the nucleus to the point where the electron cloud ends
electron affinity
the amount of energy released when an atom in the gaseous phase gains an electron to form a negative ion
electrons negativity
the measure of the tendency of an atom to attract bonding electrons
first ionisation energy
the amount of energy required to remove the first electron from an tom in its gaseous state to from a positive ion
periodicity
quality or character of being repeated at intervals
halide
binary compound of a hologram with another element or group of elements
covalent bonding
a sharing of at least one pair of electrons by two non metal atoms
ionic bonding
a transfer of electrons and subsequent electrostatic attraction
metallic bonding
electrostatic attraction between the positively charged atomic nuclei of metals atoms and a sea of delocalised electrons
delocalised electron cloud
electrons that are not at a specific point in a group of atoms
covalent molecular structures
crystal lattice that consist of separate molecules
covalent network structures
crystal lattice that consists of giant repeating lattices of covalently bonded atoms
empirical formulae
shows the simplest ratio of atoms in the compound
non-polar (pure) covalent bonding
equal sharing of bonding electrons
polar covalent bond
unequal sharing of bonding electrons
law of conservation of mass
the total mass of substances taking part in a chemical reaction is conserved during the reaction
chemical change
a change in which the chemical nature of the substances involved changes, new chemical substances are formed
physical change
a change that does not alter the chemical nature of the substance, no new chemical substances are formed
molecular formula
concise way of expressing information about the atoms that make up a particular covalent molecular compound
molecule
when atoms share electrons, are bonded covalently the resulting collection of atoms is known as molecule
oxide
an ion of oxygen
valency
the number of electrons in the outer shell of an atom which are able to form bonds with other atoms
chemical bond
physical process that causes atoms to be attracted to eachother and held together in more stable chemical compounds called molecules
group
vertical column on the periodic table
valence electrons
electrons found in the outermost energy level of an atom that can participate in forming chemical bonds with other atoms
pauli’s exclusion principle
electrons have a property of spin and two electrons must have opposite spin to share a subshell
hunds rule
electrons would rather be in a subshell on their own than share the orbital in the same energy level
neutron
particle found in the nucleus of an atom it has no electrical charge
electron
smallest particle that makes up an atom and is found outside the nucleus it’s negatively charged
proton
positively charged particle found in the nucleus
atomic number
number of protons in an atom
kinetic molecular theory
All matter is composed particles which have a certain amount of energy which allows them to move at different speeds depending on the temperature. there are spaces between the particles and also attractive forces between particles when they come close together
brownian motion
random motion of particles suspended in a liquid or gas resulting from their collision with quick atoms or molecules in the gas or liquid
metalloids
elements with mostly non-metallic properties and their distinguishing characteristic is that their conductivity increases as their temperature increases
compound
a group of 2 or more atoms attracted by relatively strong bonds the atoms are combined in definite proportions
element
a substance that cannot be broken down into other substances by chemical means
homogenous mixture
a mixture that is uniform, and the different components cannot be seen
heterogenous mixture
a mixture that consists of two or more substances that is non-uniform and the different components of the mixture can be seen
mixture
a combination of two or more substances where these substances are not bonded and no chemical reaction occurs between them
