Which phrase describes an al atom?

a. a negatively charged nucleus, surrounded by negatively charged electrons

b. a negatively charged nucleus, surrounded by positively charged electrons?

None of the given options describe any atom. The phrase which describe an atom is "a positively charged nucleus surrounded by negatively charged electrons".

Explanation:

Atom is a smallest indivisible particle which is made up of many sub particles. The main sub particles are Protons, Neutrons and Electrons. Protons are positively charged, neutrons doesn't carry any charge hence neutral and electrons are negatively charged. Protons and neutrons are present in nucleus, therefore making the nucleus positively charged, while, electrons revolve around the nucleus in orbit hence being negatively charged particles surrounds the positively charged nucleus.