Chemistry Synopsis: Compounds and Atomicity

Flashcards covering the definition of compounds, properties of chemical combinations, atomicity, and common chemical formulas based on the provided lecture transcript.

What is the definition of a compound?

A compound is a substance composed of two or more different elements, chemically combined in a fixed proportion by weight.

How can the constituents of a compound be separated?

The constituents of a compound can be separated only by chemical reactions but not by physical changes.

How do the properties of a compound like Sodium chloride compare to its constituent elements?

The properties are different; Sodium is a soft metal that reacts violently with water and Chlorine is a poisonous gas, but Sodium chloride is a non-poisonous white crystalline compound used for cooking.

What two different compounds can be formed when Hydrogen and Oxygen are combined chemically under different conditions?

Water ($H_2O$) and Hydrogen peroxide ($H_2O_2$).

Why are molecules of compounds referred to as heteroatomic or heteronuclear?

They are made up of different elements.

What is the definition of atomicity?

The number of atoms present in one molecule of an element or compound is called atomicity.

What is the atomicity of Ozone ($O_3$), Phosphorous ($P_4$), and Sulphur ($S_8$)?

Ozone has an atomicity of $3$, Phosphorous has $4$, and Sulphur has $8$.

What is the atomicity of Methane ($CH_4$)?

$$5$$

In a chemical formula, what does a numeral written on the left hand side before the formula represent?

It represents the number of molecules of the compound.

In the formula $Al_2(SO_4)_3$, how many atoms of each element are present in one molecule?

Two atoms of Aluminium, three atoms of Sulphur, and twelve atoms of Oxygen.

In three molecules of Potassium nitrate ($3KNO_3$), what is the total number of various atoms?

Three atoms of Potassium, three atoms of Nitrogen, and nine atoms of Oxygen.

What is the chemical formula for Nitric acid?

$$HNO_3$$

What is the chemical formula for Sulphuric acid?

$$H_2SO_4$$

What is the common name and formula for Sodium carbonate ($Na_2CO_3 \cdot 10H_2O$)?

Washing soda; $Na_2CO_3 \cdot 10H_2O$

What is the formula and common name for Copper sulphate?

$CuSO_4 \cdot 5H_2O$; Blue vitriol

What is the common name for the compound $KNO_3$?

Nitre