elements, compounds and mixtures

Question 1

what is an element?

Answer 1

cannot be broken down into two or more simpler substances by chemical means and consists only one type of atom

Question 2

what are metalloids?

Answer 2

elements which have both metallic and non-metallic properties

Question 3

what do metals look like?

Answer 3

shiny and lustrous appearance

Question 4

what do non-metals look like?

Answer 4

dull and non-lustrous appearance

Question 5

what states are metals in?

Answer 5

solids at room temperature with high melting and boiling points except mercury, sodium and potassium

Question 6

what states are non-metals in?

Answer 6

gases or liquids at room temperature with low melting and boiling points except carbon and silicon)

Question 7

what is the texture of metals?

Answer 7

malleable and ductile

Question 8

what is the texture of non-metals?

Answer 8

brittle (if solid)

Question 9

how do metals conduct heat and electricity?

Answer 9

good conductors of heat and electricity

Question 10

how do non-metals conduct heat and electricity?

Answer 10

usually poor conductors of heat and electricity

Question 11

how do elements exist?

Answer 11

monoatomic elements or molecules of elements which are pure substances made up of two or more atoms of the same elements chemically joined together

Question 12

what is a compound?

Answer 12

a pure substance containing two or more elements that are chemically combined in a fixed ratio

Question 13

what kind of properties do compounds have?

Answer 13

a compound has different properties from the elements that form it

Question 14

what is a mixture?

Answer 14

contains two or more substances physically mixed together without fixed compositions and can be separated by physical means

Question 15

what is formed when a substance is contaminated with impurities?

Answer 15

mixture is formed

Question 16

what is the effect of impurities on the melting point of a pure substance?

Answer 16

lower than the pure substance and it melts over a range of temperatures

Question 17

what is the effect of impurities on the boiling point of a pure substance?

Answer 17

boiling point of impure substance is higher than the pure substance and it boils over a range of temperatures

Question 18

how do compounds and mixtures differ in terms of separation?

Answer 18

compounds can only be separated by chemical methods, mixtures can be seprarted into its components by physical means

Question 19

how do compounds and mixtures differ in terms of formation?

Answer 19

a chemical reaction takes place when a compound is formed and mixtures have no chemical change when they are formed

Question 20

how do compounds and mixtures differ in terms of composition?

Answer 20

compounds have a chemical composition that is fixed. mixtures have a varying proportion of the constituents

Question 21

how do compounds and mixtures differ in terms of properties?

Answer 21

compound properties are different from their constituent elements and mixture properties are the same as their constituent substances

Question 22

how do compounds and mixtures differ in terms of mp/bp?

Answer 22

compounds melt/boil at a fixed temperature and mixtures melt/boil over a range of temperatures