Please help me understand this "Drag and drop each element symbol to its correct location on the dichotomous key". Symbols

Br Li As Ca Sb Mg Mn V Na K Sc I S Y

1. Conductors (Yes) : Li, Ca, Mg, Mn, V, Sc, Y, Na, K

a) Energy level 2 = Li

b) Energy level 3: Na, Mg

b. (i) One valence electron = Na

b. (ii) Two valence electrons = Mg

2. Conductors (No) : Br, I, S, As, Sb

a) Energy level 3 = S

b) Energy level 4: Br, As

b. (i) Seven valence electrons = Br

b. (ii)Five valence electrons = As

Explanation:

Conductors are elements which are able to conduct heat and electricity easily. They are usually metallic elements.

From the list of elements, the metals are: Li, Ca, Mg, Mn, V, Sc, Y, Na, K.

From the list of conductors, Li alone has the energy level of 2.

Na and Mg both have energy level of 3 but Na has one valence electron while Mg has two.

Non-conductors or poor conductors do not allow either heat or electricity to pass through them easily. They are usually the non-metals and semimetals or metalloids.

From the list of elements, the poor conductors are: Br, I, S, As, Sb

Only the element S, has an energy level of 3. Both Br and As have energy levels of 4 each. However, Br has seven valence electrons while As has five valence electrons.

The elements identified can be used to fill the dichotomous key attached below.

answer; 4 electrons;