Elements, Compounds, Mixtures

Question 1

what is an element?

Answer 1

it consists of one type of atom only and cannot be separated into simpler substances

Question 2

what are the differences between compounds and mixtures?

Answer 2

1. compounds are broken down by chemical methods while mixtures are separated by physical methods
2. compounds have a fixed composition while mixtures don’t
3. compounds have a fixed m.p. and b.p. while m.p. and b.p. for mixtures occurs over a range of temperatures
4. heat is absorbed/released when compound is formed but not for mixtures
5. compounds have diff properties from elements that formed it while mixtures hv similar properties from substances that formed it

Question 2

what is a compound?

Answer 2

it consists of 2 or more types of atoms and 2 or more elements chemically combined together in a fixed ratio

Question 2

what is a mixture?

Answer 2

they consists of two or more substances that are not chemically combined e.g. alloys, air , salt water

Question 3

what are the properties of metals?

Answer 3

they have high m.p. and b.p. (except grp 1 metals and mercury), good conductor of electricity and heat, malleable

Question 3

what is the definition of malleable?

Answer 3

can be hammered into different shapes without breaking (flexible)

Question 4

why are metals malleable?

Answer 4

in pure metals, atoms are of same size and are packed in regular layers. Hence, layer of atoms can slide over each other easily when force is applied

Question 5

what is an alloy?

Answer 5

it is a mixture of metal and one or more other element

Question 6

what are examples of alloys?

Answer 6

steel (iron and carbon) & brass (zinc and copper)

Question 7

why are alloys stronger and less malleable than metals?

Answer 7

alloys have different elements which have diff atom sizes, thus disrupts the regular arrangement and makes it harder for layers of atoms to slide over each other when force is applied