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Metals have many uses.

Bonding - Metallic

This Chemistry quiz is called 'Bonding - Metallic' and it has been written by teachers to help you if you are studying the subject at high school. Playing educational quizzes is a user-friendly way to learn if you are in the 9th or 10th grade - aged 14 to 16.

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This quiz looks specifically at metallic bonding. It's difficult to imagine life without metals, we use them in practically every aspect of our lives. Virtually everything involves metals in some way but what makes them so useful? In a word - bonding. The arrangement of their atoms gives metals certain characteristics which are very useful to us. High melting and boiling points, reflection of light, conduction of heat and electricity - these are all properties that we take advantage of in some way.

In metals, the atoms are packed together really closely and this causes some of the outer electrons to break free and float around within the structure of the metal. We say that the electrons are delocalised. Because they have lost electrons, metal atoms are in fact metal ions, but you don't notice this because of the delocalised electrons. Since there are as many delocalised electrons as metal ions, the overall charge is still neutral.

Normally, the motion of the electrons is random and they can move anywhere in the metal. At high school level, the structure is often described as being 'metal ions in a sea of electrons'. The attraction between the 'sea' of electrons and the metal ions is very strong and we call it metallic bonding.

The positive metal ions are free to slide over one another and this makes metals malleable and ductile. The sea of electrons is spread throughout the metal, and so when it is pulled into wires, hammered to make it thinner or bent into a new shape, the overall composition and structure of the metal is not changed. The metal ions will have been rearranged but the sea of electrons adjusts to the new arrangement, keeping the metal intact. Some metals can be beaten into very thin sheets of foil without breaking. A good example of this is beating gold to make gold leaf. This can only be done because of metallic bonding.

The sea of electrons present in metallic bonding makes metals good conductors of heat. Heat is simply an area where particles have a greater kinetic energy (energy of movement) than their neighbors. So when you heat part of a piece of metal, the ions and electrons have more kinetic energy. The electrons will therefore move faster and further than they did when they were cooler, carrying the extra kinetic energy through the metal. At the same time, because the metal ions are so closely packed, they vibrate more and as they hit neighboring ions, they too transfer the heat through the metal.

Metallic bonding also helps to explain why metals are able to conduct electricity. If you connect a piece of metal to an electrical potential difference (a voltage) e.g. an electrical cell, the electrons will move from the negative pole to the positive pole. So now the movement of electrons is less random and they all flow in the same direction through the metal which we recognize as an electrical current. Electrons are also affected by magnetic fields so when a metal is moved in a magnetic field, the delocalised electrons all tend to move in the same direction - this is how a generator or dynamo works.

Have a go at this final quiz on bonding and see how well you understand the arrangement of atoms in metallic bonding.

1 .

Why do metals conduct electricity?

The positive metal ions are free to move

The negative electrons are free to move

All the constituent parts can move through the metal

The positive protons are free to move

The electrons that make up the 'sea' of delocalised electrons are free to move. This allows conduction of both heat and electricity

2 .

What does malleable mean?

Can be stretched into wires

Can be bent or hammered into shape

Is easily shattered

Is shiny

Most metals are malleable

3 .

Pick the correct statement about the arrangement of particles in a metal.

The particles are arranged randomly and far apart

The particles are arranged regularly and far apart

The particles are arranged regularly and close together

The particles are arranged randomly and close together

Metals usually have higher densities than non-metals because the particles are so closely packed together

4 .

One drawback of superconductors is...

their behavior is erratic

they only work at VERY low temperatures

they could enable super fast transmission of electricity

they could enable loss free power transmission

To put metals into a superconducting state, extremely low temperatures close to absolute zero are required. If it becomes possible to make superconductors that work at temperatures above 0^oC it would really change the world

5 .

If a potential difference is applied to a metal...

the fixed electrons will stay in place and no current will pass through the metal

the negative ions will move through the metal carrying the electrical current

the delocalised ions will move through the metal carrying the electrical current

the delocalised electrons will move through the metal carrying the electrical current

They are attracted to the positive pole. As they leave the metal, fresh electrons are added via the negative pole

6 .

Metals have...

low melting points because they have weak bonds

low melting points because they have strong bonds

high melting points because they have weak bonds

high melting points because they have strong bonds

The strong bonds make it more difficult for the particles to move further apart - requiring more energy - raising the melting point. There are exceptions and the metal mercury is already molten at room temperature

7 .

The bonding in metals is due to a strong attraction between...

positive metal ions and a sea of negative electrons

positive metal atoms and a sea of negative electrons

negative metal atoms and a sea of positive electrons

negative metal ions and a sea of negative electrons

Remember that opposites attract

8 .

Superconductors...

work at any temperature

conduct heat better than other materials

have little or no resistance

conduct an orchestra really well

In conductors, electrical energy is lost because of the heating effect caused by resistance. In a superconductor, hardly any electrical energy is lost making electricity transmission much more efficient

9 .

Metals are malleable because...

a large amount of energy is required to slide one layer of electrons over another

little energy is required to slide one layer of electrons over another

little energy is required to slide one layer of ions over another layer

a huge amount of energy is required to slide one layer of ions over another layer

You can immediately dismiss the first two options because they are talking about layers of electrons. In metallic bonding, it is the metal ions that are in layers, the electrons are randomly arranged

10 .

What type of bonding is present in metals?

Covalent

Ionic

Hydrogen

Metallic

The majority of elements have this type of bonding

Author: Kate Gardiner