Question

read the passage and answer the next two questions. during a classroom experiment, a burning magnesium ribbon was dropped into a glass test tube filled with oxygen. a bright white flame was produced. a white powdery substance formed at the end of the reaction. which of the following statements about the element from which the ribbon was made, are true? select all that apply
it has three valence electrons
it has two valence electrons
it belongs to the third group
it belongs to the third period

Explanation:

Step1: Determine the element

The element is magnesium (\(Mg\)).

Step2: Analyze valence electrons

Magnesium has an atomic number of \(12\). Its electron configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}\). The outermost shell (\(n = 3\)) has \(2\) electrons. So, it has two valence electrons.

Step3: Analyze group and period

In the periodic table, elements are grouped based on the number of valence electrons. Magnesium has \(2\) valence electrons and belongs to Group \(2\) (not Group \(3\)).
For the period, the principal quantum number (\(n\)) of the outermost shell gives the period number. Since the outermost electrons are in \(n=3\), it belongs to the third period.

Answer:

It has two valence electrons; It belongs to the third period.