Atomic structures

4. the horizontal row of the periodic table that an element is in
6. the number of the vertical column that an element is in on the periodic table
7. a subatomic particle with negligible mass and a relative charge of -1
9. atoms of the same element that have the same proton number but a different nucleon number
11. an uncharged subatomic particle present in the nucleus of atom -
12. a substance formed by the chemical combination of two or more elements in fixed proportions.

1. the number of proton in the nucleus of an atom.
2. a shorhand method of describing the arrangement of electron within the electron sheells.
3. a subatomic particle with a relative atomic mass of 1 and a charge of +1 found in the nucleus of all atoms.
5. a substance that cannot be further divided into simpler substances by cheimcal methods.
8. a model of the atom in which electron can only occupy certain shells.
10. the allowed energies of electron in atoms-electrons fill these shells starting with the one closest to the nucleus.