Which electron configuration represents a selenium atom in an excited state?(1) 2-7-18-6(2) 2-7-18-7(3) 2-8-18-6(4) 2-8-18-7

1 answer:

5 0

(2) 2 - 7 - 18 - 7 does, because the electron from the L shell jumped to the N shell, which requires energy.

The rest of them are either different types of atoms (different elements) or are not the excited state (ground state)

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Explain why CaCl2 is likely to have properties similar to those of CaBr2

qaws [65]

Answer:

Because both CaCl2 and CaBr2 both contain elements (Chlorine and Bromine) from the same group (group 7)

Explanation:

Elements are placed into different groups in the periodic table. Elements in the same group are those that have the same number of valence electrons in their outermost shell and as a result will behave similar chemically i.e. will react with other elements in the same manner.

Chlorine and Bromine are two elements belonging to group 7 of the periodic table. They are called HALOGENS and they have seven valence electrons in their outermost shell. Hence, when they form a compound with Calcium, a group two element, these compounds (CaCl2 and CaBr2) will possess similar properties because they have elements that are from the same group (halogen group).

4 0

3 years ago

If 13.0 g of MgSO4⋅7H2O is thoroughly heated, what mass of anhydrous magnesium sulfate will remain?

Paul [167]

6.349 g mass of anhydrous magnesium sulfate will remain.

<h3>What are moles?</h3>

A mole is defined as 6.02214076 × 1023 of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.

Molar mass MgSO₄.7 H₂O = 246.52 g/mol

$Moles =\frac{mass}{molar \;mass}$