Metals and Alloys

Which statement best describes metallic bonding in a metal?

• Attraction between negative metal ions and protons in the nucleus

• Attraction between positive metal ions and a sea of delocalised electrons

• Sharing of electrons between pairs of specific atoms to form molecules

• Attraction between neutral atoms arranged randomly

In a pure metal, how are the outer-shell electrons described and what does this allow them to do?

• Localised and fixed to each atom

• Delocalised and free to move through the whole structure

• Shared only between two neighbouring atoms

• Bound to impurities making the metal harder

Which diagram caption correctly identifies the components in a giant metallic structure?

• Big circles are carbon atoms; small circles with ‘e’ are positive ions

• Big circles with ‘+’ are positive metal ions; small circles with ‘e’ are delocalised electrons

• All circles are neutral metal atoms; ‘e’ labels empty spaces

• Big circles are delocalised electrons; small circles are neutrons

Why do most metals have high melting and boiling points?

• Because atoms are arranged randomly and slide easily

• Because giant structures with strong metallic bonding require a lot of energy to break

• Because delocalised electrons reduce attractions between particles

• Because metals always contain impurities that raise melting point

What structural feature of pure metals allows them to be bent and shaped?

• Atoms arranged in layers that can slide

• Presence of carbon atoms between layers

• Random arrangement of atoms

• Weak forces between neutral atoms

Which statement explains why alloys are harder and stronger than pure metals?

• Alloys contain only one type of atom so layers slide easily

• Different-sized atoms in alloys distort the layers, requiring greater force to slide

• Alloys have no delocalised electrons so they cannot conduct

• Alloys melt at lower temperatures so they resist force better

Which statement about pure metals and alloys is correct?

• Pure metals are usually harder than alloys

• An alloy is a mixture of chemical elements of which at least one is a metal

• Most metals in everyday use are pure metals

• Shape memory alloys are used only in construction

Which statement best explains why ionic substances have high melting points?

• They consist of simple molecules with weak forces.

• They contain strong electrostatic forces of attraction in all directions between oppositely charged ions.

• They have free electrons that move easily.

• They contain only neutral atoms with no bonding.

What happens to the electrical conductivity of an ionic compound when it is melted or dissolved in water?

• It does not conduct because ions are fixed in place.

• It conducts electricity because the ions are free to move and carry charge.

• It conducts only when cooled below 0°C.

• It becomes an insulator due to broken bonds.

Ionic bonding typically occurs between which types of elements?

• Non-metal and non-metal

• Metal and non-metal

• Metal and metal

• Noble gas and metal