chap4: element, compound, mixture

Question 1

what is an element

Answer 1

element is a pure substance that cannot be broken down into 2 or more simpler substances

Question 2

what is a compound

Answer 2

compound is a pure substance that is made of 2 or more elements chemically combined in fixed ratio

Question 3

what is mixture

Answer 3

mixture is made up of 2 or more substances that is not chemically combined

Question 4

what are molecules?

Answer 4

molecule is made of a group of 2 or more atoms chemically combined

Question 5

what is diatomic molecules?

Answer 5

made up of 2 atoms that are chemically combine, they can be same or different

Question 6

what does nucleus of atom contain

Answer 6

neutron and protons

Question 7

properties of metal

Answer 7

high melting and boiling point
shiny
ductile
good conductor of heat and electricity
malleable

Question 8

properties of non-metals

Answer 8

dull
poor conductor of heat and electricity
low melting and boiling point
brittle

Question 9

decomposition of compounds

Answer 9

thermal decomposition - heat is used to break down compounds into elements
compounds can be broken down using electricity by process called electrolysis