atomic homework. need help.?

Question

i have a few questions. if you can please please help me. thx loads.

Does a atom have a greater mass if it has more neutrons, protons or electrons?

What is the charge on the ion that the element forms? (the element is Selenium)

and lastly, why do all three hydrogen isotopes have similar chemical reactions?

please help me. thanks

Answer 1

Does a atom have a greater mass if it has more neutrons, protons or electrons? From wikipedia:

Mass of a proton=1.6726 × 10−27 kg
Mass of a neutron=1.6749 × 10-27 kg
Mass of an electron=9.109 × 10–31 kg

What is the charge on the ion that the element forms? (the element is Selenium)

You should learn charges as they relate to column on periodic table: column 1A=+1, column 2A=+2, column 3A=+3, column 5A=-3, column 6A--2, column 7A=-1

The above is true for all metals and nonmetals, but not transition metals.

and lastly, why do all three hydrogen isotopes have similar chemical reactions

Isotopes are atoms with same number of protons and electrons, but diff. # of neutrons. Chemical reactions occur with changes in valence electrons, so neutrons have little influence.

Answer 2

A) i think you misinterpreted that. anyways, Protons=neutrons in weight, and electrons are VERY VERY light (almost 0 for all intents and pruposes)

B) it depends on if it gains or loses electrons

C) all 3 h-isotopes have similar chem. properties because they have the same number of vailience electrons (i think i misspelled that)

vailience electrons are the ones on the outer shell