2.1 Structure and Bonding Flashcards
Are the melting points of giant covalent substances very high or very low?
Very high as it takes a lot of energy to break the strong covalent bonds in the lattice.
Does diamond conduct electricity?
No, as it has no free electrons since each carbon atom forms 4 bonds.
Whats the difference between ionic and covalent bonding?
Ionic bonding is the transfer of electrons wheras covalent is the sharing of electrons.
Give three examples of giant molecular substances
Silicon dioxide ( sand), diamond, graphite
Why does graphite conduct electricity?
Yes, because it has delocalised electrons between the layers of carbon atoms. Each carbon atom only forms 3 bonds.
True or false? Graphite is softer than diamond.
True, this is because graphite has layers of carbon atoms that can slide over each other easily
Which type of substances bond covalently?
Non-metals
Give three examples of simple covalent molecules?
Water, carbon dioxide and methane
What happens when a metal and non- metal ironically bond?
When positive and negative ions attract to each other and bind together
What is each ion surrounded by?
Oppositely charged ions
What are the ions held in place by?
Electrostatic attractions forming an ionic crystal lattice
When do atoms turn into ions?
When they lose or gain an electron
How do you show ionic bonding?
Dot and cross diagram
What is the overall charge of an ionic compound
0
What is the formula of sodium ion?
Na+
What is formula of a chlorine ion?
Cl-
Are the melting points of ionic substances very high or very low?
High
What happens when a metal and non- metal ionically bond?
The metal transfers electrons to the non-metal and becomes positively charged. The non-metal becomes negatively charged.
What are the typical properties of ionic substances?
They have high melting and boiling points and conduct electricity when molten or in aqueous solution.
Why do ionic compounds have high melting and boiling points?
They have strong electrostatic attractions between oppositely charged ions. These take a lot of energy to overcome.
Why do they not conduct electricity when solid?
The ions are not free to move.
Why do simple covalent molecules have low melting and boiling points?
The forces of attraction between molecules (intermolecular forces) are weak so do not require much energy to overcome them.
What is the common arrangement for giant covalent structures?
They are commonly arranged into giant regular lattices: extremely strong structures, their strength caused by the many bonds inside these structures.
