It has been suggested that heating of NaCl in a flame might follow these steps. NaCl(s) NaCl(g)
NaCl (g) → Na(g) + Cl(g)
Na (g) → Na*(g)
Na*(g) → Na(g) + hv (strong yellow line is near 589/590 nm) Na represents an atom of sodium in its ground state, and Na* an atom of sodium in an excited state. The (s) means solid and (g) means gas. The ground-state electron configuration for Na(g) is [Ne]3s' and the electron configuration for Na*(g) is [Ne]3p'.

(a) As the ground-state electron configuration for Na(g) is [Ne]3s', write the ground
electron configuration for Li(g). (1 mark)

(b) From the preceding information and with your answer to Question 2 in mind, the red light emitted by the flame that you observed when LiCl was heated was likely due to
(i) what process (0.5 mark)

answer: -

reaction:

na + cl ⇌ nacl

balanced chemical equation:

na + 2cl ⇌ nacl2

sodium + clorine goes to form sodium chloride (table salt).

the product is nacl2.

and the reactants are na and cl.

(note: if you don’t know what ⇌ means, read below: -

⇌(double head arrow) means reversible reaction).

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.