Complete the lewis structures of the atoms and ions by adding electrons, as needed.

a) li

b) na

c) na+

d) f-

Lewis structure are defined structure which represents the number of valence electrons present around the atom in a molecule. They are known as Lewis electron dot structures.

Valence electrons are the electrons present in the valence shell of an atom.

A) Lithium has total three electrons out of which one is valence electron as we see that from its electronic configuration.

[Li]=, For Lewis structure see figure (I)

B) Sodium has total 11 electrons out of which one is valence electron as we can see that from its electronic configuration.

[Na]= For Lewis structure see figure (II)

C) In sodium cation, there are total 10 electrons, since it will easily loose its one valence electron to attain noble gas configuration by which there will be no valence electron present in it. So, its electronic configuration becomes

For Lewis structure see figure (III)

D) In fluorine anion, there are total 10 electrons out of which 9 electrons are of its own and one electron is being added in its valence shell ,so that it can attain noble gas configuration.

 For Lewis structure see figure (IV)

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.