Name the element: 1s2 252 2p 3s2 3p6 453 3d9 O Strontium Sr
O Krypton Kr
O Tungsten W
O Copper Cu
Silver Ag
Silicon Si

Cu

Explanation:

The sublevel notation is

    1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁹

The element is unknown;

    To find the element, sum the superscipts because the indicate the electrons;

2 + 2 + 6 + 2 + 6 + 2 + 9 = 29

The element with 29 electrons is copper

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72

you need to have a picture of the atom that way we can answer it