Question

Symbol	Z	A	#p	#e	#n	Charge
Si	14	?	?	14	14	?
S^2	?	32	?	?	?	2-
Cu^2+	?	?	?	?	34	2+
?	19	?	?	19	20	?

1) Fill in columns 1-7 of the table

Answer 1

1) we know that

now

we know that

number of protons = number of electrons = atomic number = 14

so

p = 14

atomic mass = protons + neutrsons

so

A = 14 + 14

A = 28

atomic mass of Silicon (Si) = 28

so

A=28
there is no charge on the atom

so

charge = 0

2)

we know that

atomic number of sulphur = 16

so

Z= 16

now

number of protons = atomic number = 16

so

p = 16

aslo

number of electrons in nuetral atom = atomic number = 16

but

it has -2 charge

this means two electrons are added to the neutral atom

so

number of electrons is S-2 = 16 + 1 = 18

so

e = 18

now

we know that

number of nuetrons = A - p = 32 - 16 =16

so

n = 16

3)

we know that

atomic number of copper = 29

so

Z = 29

now

number of protons = atomic number = 29

so

p = 29

now

A = p + n

so

A = 29 + 34

A = 63

also

two electrons are removed from Cu to get Cu+2

so

number of electrons in Cu+2 = 27

e = 27

4)

given atomic bumber is 19

so

it is pottasium (K)

now

we know that

number of protons = atomic number = 19

so

p = 19

now

we know that

A = p + n

A = 19 + 20

A = 39

now

p = e

so

it is nuetral atom

charge = 0

so the table is

Sym     Z       A   p    e   n   char

Si        14     28   14    14    14    0

S-2      16 32   16    18     16   -2

Cu+2   29     63   29    27     34   +2

K         19     39   19    19     20    0