Given that oxygen has an atomic number of 8.

how many protons and neutrons are in the isotope 18^o, or oxygen -18?

Oxygen (O), for example, has three naturally occurring isotopes, which can be written as 8/16O, 8/17 O, and 8/18O.

Explanation:

8 protons and 10 neutrons

Explanation:

Atomic number is defined as the number of protons or number of electrons that are present in an atom.

Atomic number = Number of electrons = Number of protons

atomic number = 8 = Number of protons

Mass number is defined as the sum of number of protons and neutrons that are present in an atom.

Mass number = Number of protons + Number of neutrons

Mass number = 18 = Number of protons + Number of neutrons

Thus Number of neutrons =18 - Number of protons= 18 - 8 = 10

Thus there are 8 protons and 10 neutrons in Oxygen -18.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.