element compound mixtures

Question 1

define element

Answer 1

made out of the same atoms, a pure substance that cannot be broken down into two or mre simpler substances by chemical processes

Question 2

define compounds

Answer 2

can be broken down into its constituent elements by chemical means, eg, thermal decomposition and electrolysis. a pure substance that contains 2 or more elements chemically combined in a fixed ratio

Question 3

changing ratio of elements in a compound will

Answer 3

give it a different compound

Question 4

compounds have different

Answer 4

properties from the elements that form it

Question 5

silver =

Answer 5

lustrous

Question 6

decomposition of compounds mean

Answer 6

breaking down compounds into elements or simpler compounds

Question 7

thermal decomposition

Answer 7

involves heating a compound strongly

Question 8

electrolysis

Answer 8

uses electricity to break down a compound (electrolysis of water to produce hydrogen and oxygen)

Question 9

define mixtures

Answer 9

made of two or more substances (elements or compounds) that are not chemically combined) (aqueous sodium chloride (salt)

Question 10

define alloy

Answer 10

mixture of metals with other elements (metals or non metals) (steel and brass)

Question 11

physical property of mixture

Answer 11

same as its constituent elements

Question 12

physical property of compounds

Answer 12

different from constituent elements

Question 13

how to change mp and bp

Answer 13

add impurities

Question 14

difference in mixtures and compounds

Answer 14

methods of separation (physical and chemical) , properties (same or different from constituent elements), energy change (absence or presence of chemical reaction), composition (fixed or non fixed proportions of elements)

Question 15

macro (elements) can exist as

Answer 15

atoms or molecules (O2)

Question 16

what is an atom

Answer 16

smallest particles of an element that has the chemical properties of that element.

Question 17

each element contains only

Answer 17

one type of atom

Question 18

the atom of an element is different from

Answer 18

that of another element

Question 19

Noble gas are

Answer 19

elements that exist as individual atoms (monoatomic elements)

Question 20

molecules of elements =

Answer 20

same atoms

Question 21

molecules of compounds =

Answer 21

different compounds

Question 22

diatomic molecule

Answer 22

2 atoms

Question 23

triatomic molecule

Answer 23

3 atoms

Question 24

polyatomic molecule

Answer 24

3 or more atoms

Question 25

polyatomic ion

Answer 25

1 ion with many elements (NH4+)

Question 26

compounds are made of

Answer 26

ions and molecules

Question 27

pure substance only consists of

Answer 27

1 element or one compound

Question 28

physical state of metals

Answer 28

mostly solids except mercury

Question 29

energy change takes place when a compound is formed ( get hot or cold), what about mixtures

Answer 29

energy change does not occur

Question 30

mixtures retain chemical properties of their constituent elements, what about compound

Answer 30

different physical and chemical properties

Question 31

no chemical reaction takes place during the formation of mixtures, what about compound

Answer 31

heat and light energy usually gives off