atomic number: the number of protons in an element
mass number: number of protons plus number of neutrons in an element
isotope: contains the same number of protons but differs in nuetrons, chemically identical.
ion: an atom which has lost or gained electrons to become a charged species. When metals lose electrons they bcome cations, when non metals gain electrons they become anions.
gamma radiation: an electromagnetic wave, highly penetrating , can mutate DNA.
relative isotipic mass: the mass of an isotope of an atom compared to one twelth of mass of an atom of carbon - 12
relative atomic mass: then mean mass of an atom and it's isotopes compared to one twelfth of an atom of c-12
ionisation energy: energy needed to rip an electron away from a metal leaving a posotive ion when in gaseous state.
Group 7 - the halogens
State at room temp - pale yellow gas
volatility - yes due to low van Der Waals between mollecules.
state at room temp - green gas
Tb: - 35
volatility - yes, low VDW's between mollecules.
state at room temp - orange liquid
volatility - yes despite increased VDW'S Br2 liquid becomes Br2 gas easily- VDW'S still low enough
state at room temp - shiny grey solid
volatility - no, increased VDW's, more energy needed to overcome attracins between I2 mollcules.
permanant dipole and melting point
presence of a permanant dipole means there will be an attraction to another polar mollecule.
This extra attraction means you will need more energy to loosen bond, so melting point increases.