Bonding Flashcards
(22 cards)
Why do metals have a high boiling and melting point?
The metallic lattice is held together by a strong electrostatic attraction between positive and negative ions and the delocalised sea of electrons. Therefore a large amount of energy is required to disrupt these bonds.
What is the structure of a metallic bond
Metallic lattice- electrostatic attraction between delocalised valence e- and the positive ions in the metallic lattice hold the structure together.
Why do metals conduct electricity
For something to conduct electricity it must have freely moving charged particles. In metallic bonding there is delocalised electrons freely moving through out the lattice and can carry charge.
Note: for molten state both e- and cations can move and act as charge carriers
Why are metals malleable and ductile?
Due to non-directional bonding the structure doesn’t change when a force acts upon it. The layers may slide but the electrostatic attraction remains the same.
What are the properties of metals
-high melting and boiling point
-good conductors if heat and electricity
-malleable and ductile
-high density
Properties of ionic compounds
-hard and brittle
-high melting and boiling points
-don’t conduct electricity at solid state
-conduct electricity at molten and aqueous state
-can be soluble in water
What is the structure of ionic compounds
3D crystal lattice- ionic compounds consist of positive and negative ions arranged in a crystal lattice
Why are ionic compounds hard but brittle
The ionic bonds are strong and have a high electrostatic attraction making the compound hard
The brittleness results from the arrangement of the ions in the lattice being disturbed. An applied force brings ions of the same charge closer together so the crystal lattice can shatter
Why do ionic compounds have a high melting point
The forces of attraction between the oppositely charged ions are so strong that large quantities of heat have to be applied to disrupt the lattice and separate the ions
Ionic solubility in water- can vary
When the soluble ionic compound is added to water the ions break away from the lattice and mix with the water molecules
Can ionic compounds conduct electricity in a solid state? why or why not
No they can’t, because in the solid state ions are trapped in fixed positions and have no free flowing charged particles so no current will flow
Can ionic compounds conduct electricity in molten/ aqueous state? Why or why not
Yes, in both of those states ions are mobile and move towards oppositely charged electrodes so they can carry the current
Which of the following would have the higher melting point? KF or CaO
CaO had a larger charge meaning they have a stronger attraction force and therefore a stronger bond. A stronger bond requires more heat energy to over come the attraction force.
What is covalent bonding
Covalent bonding is the electrostatic attraction between shared electrons and the nuclei of atoms. It is formed between non-metals and is a strong bond
What is metallic bonding
The bonding between 2 metals, it is strong
What is ionic bonding
The bonding between a metal and non metal
What are the properties of covalent molecular substances
-low melting and boiling pints
-non conductors of electricity is both solid and liquid state
-form solids that are soft
-variable solubility in water
-many have an odour
The difference between intermolecular and intramolecular forces
Inter- between the ions, eg. water and phosphorus
Intra- within the ions- hydrogen and oxygen in water
Why do covalent bonds have low melting and boiling points
Little energy is needed to overcome the weak intermolecular forces between molecules
-in meeting or booking which are PHYSICAL CHANGES no chemical bonds are broken
Why don’t covalent molecules conduct electricity
Delocalised, free flowing particles must be present for an electrical current to be conducted. In covalent substances molecules are neutral there are no ions and electrons are localised therefore charger can’t flow bc there are no free moving particles
Are covalent bonds soluble in water
Usually low or insoluble
Are metallic bonds soluble
No
