CAO: Chemical Formulae and Valencies Quiz with Flashcards

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the combining capacity of an element known as?

Atomic number

Molar mass

Valency (correct)

Ionic charge

What does the subscript '4' in OH4 signify in the context of chemical formulas?

Number of valence shells

Number of humans held by the octopus (correct)

Number of atoms of each element

Number of valence electrons

In chemical nomenclature, what is CaO called?

Carbon oxide

Copper oxide

Calcium oxide (correct)

Cadmium oxide

If an octopus represents an element with valency 2 and humans represent an element with valency 1, what would be the correct formula for the compound formed?

OH2 Signup and view all the answers

According to the information provided, how many arms do humans have in the analogy used to explain valency?

2 Signup and view all the answers

What is the combining capacity of an atom called?

Valency Signup and view all the answers

What is the formula of carbon tetrachloride?

CCl4 Signup and view all the answers

In magnesium chloride, why is the formula MgCl2?

There are two chloride ions for each magnesium ion. Signup and view all the answers

What is the formula for aluminum oxide?

Al2O3 Signup and view all the answers

Why is the formula for calcium oxide CaO and not Ca2O2?

It simplifies to a more stable form. Signup and view all the answers

What is the formula for sodium nitrate?

NaNO3 Signup and view all the answers

Why is the formula for calcium hydroxide Ca(OH)2?

It indicates two hydroxyl groups attached to one calcium atom. Signup and view all the answers

What is the valency of the aluminum ion in Al2(SO4)3?

3+ Signup and view all the answers

How many atoms are present in a single molecule of CaCl2?

4 Signup and view all the answers

Which formula correctly represents sodium sulfide?

Na2S Signup and view all the answers

What is the molecular mass of HNO3?

$85 , \text{u}$ Signup and view all the answers

Which of the following compounds is a binary compound?

$KNO3$ Signup and view all the answers

What is the correct chemical formula for magnesium hydroxide?

$Mg(OH)2$ Signup and view all the answers

Study Notes

Ionic Compounds

Calcium oxide is composed of calcium and oxygen in a 5:2 ratio by mass
Magnesium sulphide is composed of magnesium and sulphur in a 3:4 ratio by mass
Sodium chloride is composed of sodium and chlorine in a 23:35.5 ratio by mass

Chemical Formulae

A chemical formula is a symbolic representation of a compound's composition
Valency is the combining power of an element and can be used to find out how atoms combine to form a compound
Valency can be thought of as the number of "hands" or "arms" an element has

Writing Chemical Formulae

To write a chemical formula, the constituent elements and their valencies are written first
Then, the valencies of the combining atoms are crossed over
The formula for magnesium chloride is MgCl2, indicating two chloride ions (Cl-) for each magnesium ion (Mg2+)

Examples of Chemical Formulae

The formula for carbon tetrachloride is not explicitly stated
The formula for aluminium oxide is Al2O3
The formula for hydrogen chloride is HCl
The formula for calcium oxide is CaO
The formula for sodium nitrate is NaNO3
The formula for calcium hydroxide is Ca(OH)2
The formula for aluminium sulphate is Al2(SO4)3
The formula for calcium chloride is CaCl2
The formula for potassium sulphate is K2SO4
The formula for potassium nitrate is KNO3
The formula for calcium carbonate is CaCO3

Molecular Mass and Mole Concept

Molecular mass is the sum of the atomic masses of all the atoms in a molecule
It is the relative mass of a molecule expressed in atomic mass units (u)
The molecular mass of water (H2O) is the sum of the atomic masses of hydrogen and oxygen

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers writing chemical formulas for compounds by identifying the constituent elements and their valencies, followed by criss-crossing the valencies of the combining atoms. Examples include carbon tetrachloride and magnesium chloride.