elements, compounds and mixtures Flashcards
what is an element?
cannot be broken down into two or more simpler substances by chemical means and consists only one type of atom
what are metalloids?
elements which have both metallic and non-metallic properties
what do metals look like?
shiny and lustrous appearance
what do non-metals look like?
dull and non-lustrous appearance
what states are metals in?
solids at room temperature with high melting and boiling points except mercury, sodium and potassium
what states are non-metals in?
gases or liquids at room temperature with low melting and boiling points except carbon and silicon)
what is the texture of metals?
malleable and ductile
what is the texture of non-metals?
brittle (if solid)
how do metals conduct heat and electricity?
good conductors of heat and electricity
how do non-metals conduct heat and electricity?
usually poor conductors of heat and electricity
how do elements exist?
monoatomic elements or molecules of elements which are pure substances made up of two or more atoms of the same elements chemically joined together
what is a compound?
a pure substance containing two or more elements that are chemically combined in a fixed ratio
what kind of properties do compounds have?
a compound has different properties from the elements that form it
what is a mixture?
contains two or more substances physically mixed together without fixed compositions and can be separated by physical means
what is formed when a substance is contaminated with impurities?
mixture is formed
what is the effect of impurities on the melting point of a pure substance?
lower than the pure substance and it melts over a range of temperatures
what is the effect of impurities on the boiling point of a pure substance?
boiling point of impure substance is higher than the pure substance and it boils over a range of temperatures
how do compounds and mixtures differ in terms of separation?
compounds can only be separated by chemical methods, mixtures can be seprarted into its components by physical means
how do compounds and mixtures differ in terms of formation?
a chemical reaction takes place when a compound is formed and mixtures have no chemical change when they are formed
how do compounds and mixtures differ in terms of composition?
compounds have a chemical composition that is fixed. mixtures have a varying proportion of the constituents
how do compounds and mixtures differ in terms of properties?
compound properties are different from their constituent elements and mixture properties are the same as their constituent substances
how do compounds and mixtures differ in terms of mp/bp?
compounds melt/boil at a fixed temperature and mixtures melt/boil over a range of temperatures
