Answer:
four elements
Explanation:
He = 1s²
Be = 1s² 2s²
C = 1s² 2s² 2p²
Mg = 1s² 2s² 2p⁶ 3s²
Si = 1s² 2s² 2p⁶ 3s² 3p²
Ca = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
Valence electrons are those electrons which are present in outer most electronic shell.
He, Be, Mg, Ca these four elements have 2 valence electrons.
While Si and C have four valance electrons.
According to the equation, the ratio of the reactant Cu and product CuO is 2:2, thus 1:1. Therefore to produce 2.44 mol CuO, 2.44 mol Cu is required. The molecular weight of Cu is 64. So the mass of Cu that is required to produce 2.44mol CuO is 2.44mol * 64 g/mol = 156.16 g.
Replicating experiments
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Answer:
B6Br4
Explanation:
Chemical formula gives a representation of the number of atoms that each element in a compound or molecule. In this question which is asking to give the formula of hexaboron tetrabromide, the hexa means 6 while the tetra means four.
Since the number of atoms of each element is written as a prefix before the main element, this means that the chemical formula of hexaboron tetrabromide will be B6Br4.
