atomic sturcture and the periodic table Flashcards
what is an atom
make up all substances and are the smallest part of an element that can exist
what are compounds
formed from elements by chemical reactions. chemical reactions always involve the formation of one or more substances often involve an energy change
what do compounds contain
two or more elements chemically combined in fixed proportions
what can compounds be separated into
elements by chemical reactions
what is a mixture
consists of two or more elements or compounds not chemically combined together
how can a mixture be separated
filtration crystallisation distillation fractional distillation or chromatography
what was the discovery of the plum pudding model
atom ball of positive charge with negative electrons embedded in it
what did james chadwick discover
neutrons within the nucleus
what is the atomic number
the number of protons in an atom of an element
what is the proton neutron and electron relative charge
proton - +1
neutron - 0
electron - -1
what is the proton neutron and electron relative mass
proton - 1
neutron - 1
electron - very small
what is the mass number
the sum of the protons and neutrons in a atom
what are isotopes
atoms of the same element with different numbers of neutrons
what is the relative atomic mass
an average value that takes account of the abundance of the isotope of the element
what are metals
elements that react to form positive ions