Which of these elements has an electron configuration of [kr]5s2?
barium
calcium
rubidium
strontium

The mass of a neutron is equal to the mass of a proton plus the mass of an electron. true or false false true

Sally is making a model of a magnesium atom with an atomic mass number of 24 for her chemistry class. she has foam balls for the protons, neutrons, and electrons. she has added 6 neutrons to her model so far. how many more neutrons does she need to add to complete her neutral atom of magnesium?

Define the kinetic molecular theory