carbon and its compounds

What is the atomic number of carbon?

6

What is the mass number of carbon-12?

12

What is the electronic configuration of carbon?

2, 4

What type of bonds does carbon generally form?

Covalent bonds.

What is the origin of the word carbon?

Latin carbo, meaning charcoal.

What is catenation?

The ability of carbon atoms to link with one another.

What structures can carbon chains form?

Straight chains, branched chains and rings.

What are isotopes?

Atoms with the same atomic number but different mass numbers.

Name the three isotopes of carbon.

Carbon-12, carbon-13 and carbon-14.

What is allotropy?

The existence of an element in two or more forms with different physical properties.

What are the two main crystalline allotropes of carbon?

Diamond and graphite.

Name three common forms of amorphous carbon.

Charcoal, lamp black (soot) and coke.

Why does diamond sparkle?

Its high refractive index causes strong reflection and refraction of light.

How many carbon atoms are directly bonded to each carbon in diamond?

Four, in a three-dimensional tetrahedral arrangement.

Why is diamond extremely hard?

Each carbon atom forms four strong covalent bonds in a rigid 3D network.

Why does diamond not conduct electricity?

It has no free electrons to carry electric current.

What is the density of diamond?

Approximately 3.52 g/cm³.

What happens when diamond burns in oxygen?

It forms carbon dioxide.

What happens when diamond is heated to about 1600°C without oxygen?

It changes into graphite.

What is the structure of graphite?

Carbon atoms form hexagonal layers.

How many carbon atoms are bonded to each carbon in graphite?

Three.

Why does graphite conduct electricity?

It has mobile electrons that can move through its layers.

Why is graphite soft and slippery?

Weak forces between its layers allow them to slide over one another.

Why is graphite used in pencils?

Its layers rub off onto paper, leaving a black mark.

Why is graphite used for electrodes?

It conducts electricity and is relatively chemically stable.

Why is graphite used as a nuclear reactor moderator?

It slows down fast-moving neutrons.

What is the approximate density of graphite?

2.25 g/cm³.

Why does graphite have a high melting point?

Strong covalent bonds hold the carbon atoms together within its layers.

Name some uses of graphite.

Pencils, electrodes, lubricants, crucibles and nuclear reactor moderators.

What is fullerene?

An allotrope of carbon whose atoms form closed-cage structures.

What is buckminsterfullerene?

A fullerene containing 60 carbon atoms, called C₆₀.

What is the shape of buckminsterfullerene?

A football-like spherical structure.

Who discovered fullerene, and in which year?

Robert Curl, Harold Kroto and Richard Smalley in 1985.

Name some uses of fullerene.

Superconductors, semiconductors, lubricants and catalysts.

What is one carat of diamond equal to?

0.2 g or 200 mg.

Why can synthetic diamonds sometimes be distinguished from natural diamonds?

Their characteristics and internal features may differ.

What are amorphous forms of carbon?

Forms of carbon without a regular crystalline structure.

How is wood charcoal prepared?

By heating wood with a limited supply of air.

Why is wood charcoal a good adsorbent?

Its porous structure provides a large surface area.

Name some uses of wood charcoal.

Water purification, gas masks, decolourising sugar and removing odours.

Why can charcoal be a better fuel than wood?

It generally produces less smoke and has a higher calorific value.

How is bone charcoal prepared?

By heating dried bones in the absence of air.

What is one use of bone charcoal?

Decolourising sugar juice.

How is sugar charcoal prepared?

By dehydrating sugar with concentrated sulphuric acid.

How is activated charcoal prepared?

By heating charcoal strongly and passing steam through it.

Why is activated charcoal an effective adsorbent?

Activation increases its porosity and surface area.

How is lamp black or carbon black produced?

By incomplete combustion or heating carbon-rich substances with limited oxygen.

Name some uses of lamp black.

Inks, boot polish, paints, carbon paper and tyre manufacture.

How is coke prepared?

By destructive distillation of coal—strong heating without air.

Name some uses of coke.

Fuel, metallurgical operations and electrode manufacture.

What is adsorption?

The accumulation of a substance on the surface of another substance.

What is absorption?

The uptake of a substance into the bulk of another substance.

What is the main difference between adsorption and absorption?

Adsorption occurs on the surface; absorption occurs throughout the bulk.

Why is activated charcoal used in gas masks?

It adsorbs many harmful gases and vapours.

What is a reducing agent?

A substance that removes oxygen from another substance or causes its reduction.

Name two important reducing agents made from carbon.

Coke and charcoal.

Why can carbon act as a reducing agent?

It removes oxygen from certain metal oxides at high temperatures.

What happens when hot coke reacts with carbon dioxide?

Carbon monoxide is formed: CO₂ + C → 2CO.

What happens when lead(II) oxide is heated with charcoal?

Lead is produced, forming a shiny globule.

Write the reaction between lead(II) oxide and carbon.

PbO + C → Pb + CO.

What happens when zinc oxide is heated with carbon?

Zinc is produced and carbon monoxide forms.

Write the reaction between zinc oxide and carbon.

ZnO + C → Zn + CO.

What happens when iron(III) oxide is heated with carbon?

Iron and carbon monoxide are formed.

Write the reaction between iron(III) oxide and carbon.

Fe₂O₃ + 3C → 2Fe + 3CO.

What happens when black copper(II) oxide is heated with charcoal?

It changes to reddish-brown copper.

What is the textbook equation for copper(II) oxide reacting with carbon?

CuO + C → Cu + CO.

What is another balanced equation for copper(II) oxide reacting with carbon?

2CuO + C → 2Cu + CO₂.

What happens when carbon dioxide is heated with coke?

Carbon monoxide gas forms and carbon is consumed.

Why is graphite suitable for making crucibles?

It has a high melting point.

Why is diamond used for cutting and drilling?

Its extreme hardness makes it suitable for cutting hard materials.

Name some uses of diamond besides jewellery.

Precision instruments, industrial cutting and drilling, and specialised optical applications.

What happens when diamond burns completely in oxygen?

Carbon dioxide is produced.

Why does diamond have a higher density than graphite?

Its carbon atoms form a tightly bonded three-dimensional network.

Why is diamond an electrical insulator?

Its valence electrons are held in covalent bonds and cannot move freely.

Why can graphite be used as a lubricant?

Its layers slide easily over one another.

What is the chemical symbol for carbon?

C.

What is the atomic number of carbon-12?

6.

What is the mass number of carbon-13?

13.

What is the mass number of carbon-14?

14.

What is the number of valence electrons in carbon?

Four.

Why does carbon form covalent compounds?

It shares electrons to complete its outer shell.

What is the approximate refractive index of diamond?

2.415.

What happens to diamond when heated strongly without oxygen?

At about 1600°C, it changes into graphite.

What is the appearance of fullerene C₆₀ described in the textbook?

A yellow powder.

What is the specific gravity of fullerene given in the textbook?

Approximately 1.8–2.1.

In what type of solvents is fullerene soluble, according to the textbook?

Organic solvents.

How does fullerene's reactivity compare with diamond and graphite in the textbook?

It is described as more reactive.

Why is carbon important in metallurgy?

It can reduce certain metal oxides to metals.

What observation indicates that lead has formed in the charcoal cavity experiment?

A shiny lead globule appears.

What observation indicates that copper has formed when copper(II) oxide is heated with charcoal?

The black solid changes to reddish-brown copper.

What is the role of coke in the reaction with carbon dioxide?

Coke reduces carbon dioxide to carbon monoxide at high temperature.

What is the formula of carbon dioxide?

CO₂.

What is the formula of carbon monoxide?

CO.

What is the formula of buckminsterfullerene?

C₆₀.

What are the main crystalline forms of carbon?

Diamond and graphite.

What are the main categories of carbon allotropes in this chapter?

Crystalline and amorphous forms.