The atomic mass of Oxygen is approximately 16 u.

The atomic mass of Sodium (Na) is approximately 22.99 u.

The atomic number of Carbon is 6, which is the number of protons in its nucleus.

The atomic number of Oxygen is 8.

Alkaline earth metals commonly exhibit a +2 oxidation state.

Group 1 elements commonly exhibit an oxidation state of +1.

Alkali metals are located in group 1 of the periodic table.

Halogens are located in group 17 of the periodic table.

Argon is located in Period 3 of the periodic table.

Lithium is located in period 2 of the periodic table.

Lithium is located in period 2 of the periodic table.

Sodium is in period 3 of the periodic table.

The symbol for Gold is Au.

Magnesium has a valency of 2, as it can lose two electrons.

Oxygen has a valency of 2, as it needs two electrons to complete its outer shell.

Sodium has the atomic number 11, indicating it has 11 protons.

Hydrogen has the atomic number 1.

Calcium has the highest atomic number (20) among the first 20 elements.

Francium has the lowest electronegativity among the given elements.

Chlorine is found in Group 17, also known as the halogens.

The symbol 'Fe' stands for Iron, derived from its Latin name 'Ferrum'.

The symbol 'K' represents Potassium, derived from its Latin name 'Kalium'.

Noble gases are found in Group 18 of the periodic table, characterized by their lack of reactivity due to having a full valence shell.

Bromine is a halogen, located in group 17 of the periodic table.

Neon is a noble gas, which is characterized by its lack of reactivity.