Sodium is going in group 1, period 3. It contains A. One valence electron in its 3rd energy shell B three valence electron in its 1st energy shell C. 11 protons, 11electrons , 11 neutrons D. 11 protons, 11 electrons and 23 neutrons

The correct answer is option A, that is, one valence electron in its third energy shell and option C, that is, 11 electrons and 11 protons.

Explanation:

The outermost electrons and the ones that take part in the process of bonding are termed as valence electrons. The atomic number of sodium is 11, thus, it possesses 11 protons and the atoms are neutral so it suggests that sodium has 11 electrons. By electronic configuration, it can be seen that in sodium, two electrons are present in the first shell, 8 in the second, and only one electron in the third shell, that is, 2.8.1. The electron present in the third shell is the valence electron.

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles