Please help! 1.what has 3 valence electrons and and 2 electron shells
2.what has 6 valence electrons and 3 electron shells !!!

What is the rms speed of cesium atoms that have been cooled to a temperature of 100 nk?

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?

What is the formula of the ionic compound composed of calcium cations and chloride anions