Metals, Alloys, and Bonding

Flashcards about metals, alloys, and types of bonding.

What is an alloy?

A mixture of two or more elements, at least one being a metal.

Why are pure metals relatively soft/malleable?

All the same element, so all atoms are the same type and size. This forms a regular structure of layers. Layers can slide over each other.

What is the role of delocalised electrons in metals?

They are free to move and carry charge through the whole structure.

Why are alloys harder than pure metals?

Mixture of elements with different sizes of atoms. This disrupts the regular structure of layers, so layers cannot slide over each other as easily.

Describe the structure and bonding of a metal.

Giant metallic lattice with atoms arranged in layers. Outer shell electrons are delocalised to form positive ions. Strong electrostatic forces of attraction exist between positive ions and delocalised electrons (metallic bonds).

Why do metals have high melting points?

Giant metallic structure with many strong electrostatic forces of attraction between positive ions and delocalised electrons. Lots of energy is needed to break these.

Why do metals conduct electricity?

Outer shell electrons are delocalised and are free to move, so they can carry charge through the whole giant structure.

Why do metals conduct thermal energy?

Outer shell electrons are delocalised and are free to move, so they can transfer thermal energy through the whole giant structure.

Why can metals be hammered into shape?

Layers of atoms can slide over each other, and delocalised electrons move out of the way.

What are ionic bonds?

Strong electrostatic forces of attraction between oppositely charged ions.

Why do ionic compounds have high melting and boiling points?

Giant ionic structure/lattice with many strong electrostatic forces of attraction between oppositely charged ions. A large amount of energy is needed to break the many strong bonds.

Why can ionic compounds conduct electricity when molten or in solution?

The ions are free to move, carry the charge, so charge can flow.

What is a covalent bond?

A shared pair of electrons.

Why do simple molecular substances have relatively low melting and boiling points?

Simple molecular substance with only weak intermolecular forces between molecules, so only a small amount of energy is needed to overcome the weak forces.

Why do larger molecules have higher melting and boiling points?

The intermolecular forces between molecules increase in number/strength as the size of the molecules increases. This means that more energy is needed to overcome the stronger forces.

Why do simple molecular substances not conduct electricity?

Molecules have NO overall electric charge, so charge cannot flow.

Why do giant covalent structures have high melting points?

Giant covalent structure with many strong covalent bonds. Large amounts of energy are needed to break the many strong bonds. Lots of energy needed to break the bonds.

Why is diamond very hard?

Giant covalent structure where each carbon forms four strong covalent bonds giving a hard, rigid structure.

Why is graphite soft and slippery?

Each carbon atom bonds to three others forming layers. The layers can slide over each other because there are only weak intermolecular forces between the layers.

Why does graphite conduct electricity?

Each carbon atom bonds to three others forming layers. One outer electron from each carbon is delocalised.