How does the number of valence electrons change as you move to the right across the periodic table?

As we move from left to right across the

periodic table the number of valance

electrons in an atom increase.

Explanation:

As we move from left to right across the

periodic table the number of valance

electrons in an atom increase.The

atomic size tend to decrease in same

period of periodic table because the

electrons are added with in the same

shell. When the electron are added, at

the same time protons are also added

in the nucleus. The positive charge

is going to increase and this charge

is greater in effect than the charge of

electrons. This effect lead to the greater

nuclear attraction. The electrons are pull

towards the nucleus and valance shell

get closer to the nucleus. As a result of

this greater nuclear attraction atomic

radius decreases and ionization energy

increases because it is very difficult to

remove the electron from atom and more

energy is required

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.