Question

I'm very bad with chemistry and I need some help with these practice problems.

An atom of silicon has a mass number of 28 and an atomic number of 14. How many protons and how many neutrons are in this atom

Answer 1

the atomic number is equal to the number of protons, the mass number is equal to the sum of the number of protons plus the number of neutrons.
In your case 14 protons and (28-14=14) 14 neutrons!!!

Answer 2

Thank you, could you help me with this next question.

Electron A falls from energy level X to energy level Y and releases blue light. Electron B falls from energy level Y to energy level Z and releases red light. Which transition, from X to Y or from Y to Z, has a greater energy difference?

Answer 3

I will said the blue, the blue waves usually has more energy than the red and have a higher frequency and shorter wavelenght

Answer 4

red waves had a wavelength of ~700nm and blue ~450nm, (E=hc/wavelenght) so energy is inversely proportional to wavelenght, so shorter wavelenght higher energy

Answer 5

how did you get that?

Answer 6

http://en.wikipedia.org/wiki/Light

Answer 7

ohh okay thank you