1.6 - 1.8 - Structure and bonding Flashcards
What are charged particles called?
Ions
What are ions?
Ions are charged particles formed when atoms lose or gain electrons. They can have either positive or negative charges
What is a positive ion called?
Cation
What are negative ions called?
Anions
Explain ionic bonding
When an ionic compound is formed electrons are transferred from a metal atom to a non-metal atom to form a positive an negative ions.
What is the definition of ionic bonding?
Ionic bonding is the electrostatic attraction between positive a negative ions
How to show ionic bonding?
Dot and cross diagram
What does a compound end in if it is has oxygen in it?
ate like sodium sulfate
What does a compound end in if it does not contain oxygen?
ide like sodium sulfide
What are giant ionic structures?
All ionic compounds form crystals that consist of lattices of positive and negative ions packed together in a regular way. A lattice is a regular array of ions . The lattice is held together by the strong electrostatic attractions between the positively and negatively charged ions
What are the physical properties of ionic substances?
Ionic substances have high melting and boiling points because of the strong electrostatic forces of attraction holding the lattice together. A lot of energy is needed to break the strong electrostatic forces of attraction between the oppositely charged ions in the giant ionic lattice. Ionic compounds tend to me crystalline this is reflected in the regular arrangements of ions in the lattice.
Explain the electrical conductivity of ionic substances
Ionic substances don’t conduct electricity when they are a solid because the ions are in a fixed position and are not free to move around and pass on the current. They do how ever conduct electricity when they are in the molten state. or dissolved in water. This happens because the ions then become free to move and pass on the current.
What is covalent bonding?
In a covalent bond a pair of electrons is shared between 2 atoms and their nuclei. What holds the atom together is the strong electrostatic attraction between the nuclei of the atoms that make up the bond and the shared pair of electrons.
How are covalent bonds often shown?
Dot and cross diagram
What are simple molecular structures?
molecules contain fixed number of atoms joined by strong covalent bonds. The forces between the molecules in a simple molecular structure are intermolecular forces. intermolecular forces between molecules are much weaker than covalent bonds. These intermolecular forces can easily broken. Simple molecular structures dont require much energy to break the intermolecular forces of attraction between the molecules. No covalent bonds are broken though because they are strong.
Why do melting and boiling points increase in groups?
The melting and boiling points increase as the relative molecular mass increases. As relative molecular mass increases so does the strength of the intermolecular forces
What are the other physical properties of Covalent compounds?
Covalent molecular compounds do not conduct electricity. This is because the molecules do not have any overall electrical charge because there are no ions and the electrons are held tightly in the atom so not able to move from molecule. Covalent molecular substances tend to be insoluble in water. but they are soluble in organic solvents
Describe the structure properties and bonding of Diamond.
Diamond is a pure form of carbon . Each carbon atom has four electrons in its outer shell and therefore it forms four covalent bonds. In diamond each carbon bonds strongly to four other carbon atoms in a tetrahedral arrangement. Diamond is a giant covalent structure it is not a molecule because the number of atoms joined up in diamond is completely variable and depends on the size of the crystal. Molecules always contain fixed number of atoms joined by covalent bonds. Diamond has a very high melting and boiling point . This is because of the very strong carbon-carbon covalent bonds. which extend through the whole crystal. A lot of energy is required to break these strong covalent bonds. Therefore diamond has a very high melting and boiling point. Diamond has no intermolecular forces no molecules Covalent bonds which are very strong must be broken in order to melt or boil. Diamond does not conduct electricity because there are no delocalised electrons to pass on the current.
Describe the structure properties and bonding of Graphite
Graphite is also a form of carbon but the atoms are arranged differently. Although it has a giant structure it has a layer structure. graphite is a soft material. Although the forces holding the atom together in each layer are strong. the attraction between the layers are much weaker and not much energy is required in order to break the bonds. The layers can slide over each other and can easily be flaked off. graphite has a high melting and boiling point to melt or boil graphite the whole structure has to be broken not just the layers including the covalent bonds this requires high amounts of energy because the bonds are so strong. Graphite can conduct electricity each carbon atom is joined to only 3 others. Each carbon atom uses 3 of its outer shell electrons to form 3 single covalent bonds. The 4th electron is on the outer layer and is free to move around the entire layer this is a delocalised electron the movement of them allows current to be passed on
Describe the structure properties and bonding of C60 fullerene?
C60 is a simple molecular structure it has a low melting and b
What are allotropes?
different forms of the same element
What is the definition of metallic bonding?
Metallic bonding is the electrostatic forces of attraction between each positive ion and the delocalised electrons. This holds the structure together.
What happens when two atoms of the same element bond together?
the outer electron on each metal lets say sodium become free to move throughout the whole structure electrons said to be delocalised. Electrons are no longer attached to a particular atoms pairs of atom A metallic structure consists of a lattice of positive ions in a sea of delocalised electrons
What is the structure of Metallic bonds?
Metals have giant structures. No individual molecules and all the positive ions in the lattice attract all the delocalised electrons
What are the properties of Metals
Most metals have high melting and boiling points. This means that there are strong electrostatic forces of attraction between the positive ions and the delocalised electrons. In the case of sodium only one electron per atom is delocalised leaving ions with only one positive charge on them. Magnesium has two outer electrons both of which are delocalised into the ‘sea of electrons’ leaving behind ions with a 2+ charge there is a much stronger electrostatic attraction between the 2+ ions and the delocalised electrons meaning bonding is stronger and melting point is higher.
Why does metal conduct electricity?
Metal conduct electricity because the delocalised electrons are free to move throughout the structure
Why are metals Malleable?
Metals can be changed into two different shapes this is what malleable is. When a force is applied to a peice of metal they layers of the positive ions slide over each other. This does not affect the bonding in the structure the positive ions are till attracted to the delocalised electrons.
Why are metals ductile?
can be drawn onto wires.
