Answer:
beryllium: 2 valence electrons
nitrogen: 5 valence electrons
oxygen: 6 valence electrons
fluorine: 7 valence electrons
magnesium: 2+ valence electrons
phosphorus: 5 valence electrons
sulfur: 6 valence electrons
chlorine: 7 valence electrons
Explanation:
please have look at Periodic table , you will solve it yourself !
A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral atom contains a single positively charged proton and a single negatively charged electron bound to the nucleus by the Coulomb force. Atomic hydrogen constitutes about 75% of the baryonic mass of the universe.
Answer:
Explanation:
a )
m = m₀ 
m is mass after time t . original mass is m₀ , λ is disintegration constant
λ = .693 / half life
= .693 / 1590
= .0004358
m = m₀ 
b )
m = 50 x 
= 40.21 mg .
c )
40 = 50 
.8 =
= 1.25
.0004358 t = .22314
t = 512 years .
