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
what are non-metals
elements that do not form positive ions
where are non-metals found
towards the right and top of the periodic table
where are metals found
majority of elements are metal
found to the left and towards the bottom
what are group 1
alkali metals
what are some characteristics of alkali metals
react with oxygens to create an oxide
they react with chlorine to form a white precipitate
reactivity increases when going down the group
what are group 0 called
noble gases
what are some characteristics of noble gases
they have 8 electrons in there outer shell (except helium 2)
all have full outer shells
the are unreactive and do not easily form molecules
the boiling point increases with increasing the relative atomic mass
what are group 7
the halogens
what are some characteristics of halogens
they react with metals to form an ionic compound in which the halide ion carries a -1 charge
they react with non-metals to form a covalent compound
reactivity decreases going down the group
decrease reactivity means that a more reactive halogen can displace a less reactive one in a aqueous solution of its salt
