Question

Element X is a neutral element and has 39 protons. What element is it and how many electrons does it have? (Use the periodic table)
A.
Argon – 18
B.
Yttrium – 39
C.
Platinum – 78
D.
There is not enough information to determine.
Points Possible:2.00
2.
Using the periodic table, which of the following is an isotope?
A.
C – 12
B.
Zn – 68
C.
Tb – 159
D.
Cs - 133
Points Possible:2.00
3.
Cerium has 58 neutrons and 58 protons.
A.
True
B.
False

Answer 1

I have a idea..

Answer 2

The # of protons an atom has corresponds with the atomic number of the element in the Periodic Table.
So, if I had an atom with 12 protons, I know it is Magnesium, b/c Mg's atomic # os 12.

Answer 3

For Part B, an isotope occurs when the number of neutrons in an atom doesn't equal to amount of protons. A neutral atom has same number of protons as neutrons.
So, if the number next to it isn't 2 times the atomic number, then that choice is an isotope.

For example: If I had a Carbon atom, I know it has 6 protons, b/c its atomic number is 6. But, my atom only has 5 neutrons, not 6 neutrons. So it's an isotope.
It will be labeled Carbon-11. The '11' comes from the sum of protons and neutrons.