exam non general stuff

Question 1

define a symbol

Answer 1

short form of an element

Question 2

define valency

Answer 2

the number of hydrogen atoms which can combine with or displace one atom of the element or radical to form a compound

Question 3

define radical

Answer 3

a group of elements that behaves like a single unit and shows a unity

Question 4

define chemical formula

Answer 4

symbolic representation of a molecule of a substance.

Question 5

define chemical equation

Answer 5

symbolic representation of a chemical reaction

Question 6

define relative molecular mass

Answer 6

the number of times one molecule of the substance is heavier than 1/12 the mass of an atom of carbon

Question 7

define relative atomic mass

Answer 7

number of times one atom of an element is heavier than 1/12 the mass of an atom of carbon

Question 8

name the 1st 20 elements

Answer 8

hydrogen, helium, lithium, berrylium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminium, silicon, phosporus, sulphur, chlorine, argon, pottassium, calcium

Question 9

what are isotopes

Answer 9

atoms of the same element having same atomic numbers but different physical properties

Question 10

what are the three isotopes of hydrogen

Answer 10

protium, deuterium, tritium

Question 11

define chemical bond

Answer 11

force which acts between two or more atoms to hold them together as a stable molecule

Question 12

define electrovalent bond

Answer 12

the chemical bond formed between the two atoms by transfer of one or more electrons from the atom of a metallic element to an atom of a non metallic element

Question 13

define covalent bond

Answer 13

the chemical formed due to mutual sharing of electrons between the given pair of non-metallic elements