Bonding, structure, and the properties of matter Flashcards
What is ionic bonding?
In ionic bonding the particles are oppositely charged ions. Ionic bonding occurs in compounds formed from metals combined with non-metals.
When a metal atom reacts with a non-metal atom electrons in the outer shell of the metal atom are transferred. Metal atoms lose electrons to become positively charged ions. Non-metal atoms gain electrons to become negatively charged ions. The ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 have the electronic structure of a noble gas
What is metallic bonding?
In metallic bonding the particles are atoms which share
delocalised electrons. Metallic bonding occurs in metallic elements and alloys.
What is covalent bonding?
In covalent bonding the particles are atoms which share pairs of electrons. Covalent bonding occurs in most non-metallic elements and in compounds of non-metals.
Describe the structure of the ionic compound
An ionic compound is a giant structure of ions. Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. These forces act in all directions in the lattice and this is called ionic bonding.
Describe covalent bondings structure
These bonds between atoms are strong. Covalently bonded substances may consist of small molecules.
Describe the structure of metallic compound
Metals consist of giant structures of atoms arranged in a regular pattern. The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure. The sharing of delocalised electrons gives rise to strong metallic bonds.
What does the amount of energy required to change state depend?
the strength of the forces between the particles of the substance. The nature of the particles involved depends on the type of bonding and the structure of the substance. The stronger the forces between the particles the higher the melting point and boiling point of the substance.
What are the limitations of the simple model of state?
Limitations of the simple model above include that in the model there are no forces, that all particles are represented as spheres and that the spheres are solid.
Properties of iconic compounds?
Ionic compounds have regular structures (giant ionic lattices) in which there are strong electrostatic forces of attraction in all directions between oppositely charged ions
compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds.
When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and so charge can flow.
Properties of small molecules:
Substances that consist of small molecules are usually gases or liquids that have relatively low melting points and boiling points.
These substances have only weak forces between the molecules (intermolecular forces). It is these intermolecular forces that are overcome, not the covalent bonds, when the substance melts or
boils.
The intermolecular forces increase with the size of the molecules, so larger molecules have higher melting and boiling points.
These substances do not conduct electricity because the molecules do not have an overall electric charge.
What are polymers?
Polymers have very large molecules. The atoms in the polymer molecules are linked to other atoms by strong covalent bonds. The intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature.
What substances that consist of giant covalent structures?
Substances that consist of giant covalent structures are solids with very high melting points. All of the atoms in these structures are linked to other atoms by strong covalent bonds. These bonds must be overcome to melt or boil these substances. Diamond and graphite (forms of carbon) and silicon dioxide (silica) are examples
of giant covalent structures.
Properties of Metals:
Metals have giant structures of atoms with strong metallic bonding. This means that most metals have high melting and boiling points. Metals are good conductors of electricity because the delocalised
electrons in the metal carry electrical charge through the metal. Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.
Why are alloys made?
In pure metals, atoms are arranged in layers, which allows metals to be bent and shaped. Pure metals are too soft for many uses and so are mixed with other metals to make alloys which are harder.
What is Diamonds structure?
In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity.
