C2 Flashcards
What are the three types of strong chemical bonds?
Ionic, covalent and metallic
What does ionic bonding involve in terms of particles?
Oppositely charged ions.
What does covalent bonding involve in terms of particles?
Atoms which share pairs of electrons
What does metallic bonding involve in terms of particles?
Atoms which share delocalised electrons.
When does ionic bonding occur?
In compounds formed from metals combined with non-metals.
When does covalent bonding occur?
In most non-metallic elements and in compounds of non-metals
When does metallic bonding occur?
In metallic elements and alloys.
Explain chemical bonding in terms of electrostatic forces and the transfer or sharing of electrons.
- A chemical bond is a lasting attraction between atoms,ions or molecules that enables the formation of chemical compounds.
- The bond may result from the electrostatic force between oppositely charged ions as in ion bonds or through the sharing of electrons as in covalent bonds
When a metal atom reacts with a non-metal atom what is transferred?
Electrons in the outer shell of the metal atom are transferred
Why do metal atoms lose electrons?
To become positively charged ions.
Why do non-metals lose electrons?
Non-metal atoms gain electrons to become negatively charged ions
What are the ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 similar to in terms of electronic structure?
They have the electronic structure of a noble gas (Group 0)
How can the electron transfer during the formation of an ionic compound be represented?
By a dot and cross diagram
Note:
AQA says that students should be able to draw dot and cross diagrams for ionic compounds formed by metals in Groups 1 and 2 with non-metals in Groups 6 and 7
(Check page 115)
What does the charge on the ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 relate to?
The group number of the element in the periodic table.
Note:
AQA says that students should be able to work out the charge on the ions of metals and non-metals from the group number of the element, limited to the metals in Groups 1 and 2, and non-metals in Groups 6 and 7.
What is an ionic bond?
When a metal or nonmetal react together, the metal atom loses electrons to form a positively charged ion and a non-metal gains these electrons to form a negatively charged ion. These oppositely charged ions are strongly attracted to one another by electrostatic forces.
What is an 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.
What is the structure of a single crystal of sodium chloride (table salt)
One giant ionic lattice. The Na+ and Cl- ions are held together in a regular lattice
(Check CGP 114 to see its structure in a diagram)
Note:
Students should be able to:
- deduce that a compound is ionic from a diagram of its
structure in one of the specified forms - describe the limitations of using dot and cross, ball and stick,
two and three-dimensional diagrams to represent a giant ionic
structure - work out the empirical formula of an ionic compound from a
given model or diagram that shows the ions in the structure. - Students should be familiar with the structure of sodium chloride but
do not need to know the structures of other ionic compounds.
What are covalent bonds?
- When atoms share pairs of electrons, they form covalent bonds.
- These bonds between atoms are strong.
What may covalently bonded substances consist of?
Small molecules
Note:
AQA says that students should be able to recognise common substances that
consist of small molecules from their chemical formula.
(Check CGP page 116)
What are some covalently bonded substances like?
- They have very large molecules, such as polymers and they have giant covalent structures
- Diamond and silicon dioxide have giant covalent structures
Note:
The covalent bonds in molecules and giant structures can be
represented in the following forms (Check CGP page 115 for this)
Note:
AQA says that students should be able to:
- draw dot and cross diagrams for the molecules of hydrogen,
chlorine, oxygen, nitrogen, hydrogen chloride, water,
ammonia and methane - represent the covalent bonds in small molecules, in the
repeating units of polymers and in part of giant covalent
structures, using a line to represent a single bond - describe the limitations of using dot and cross, ball and stick,
two and three-dimensional diagrams to represent molecules
or giant structures - deduce the molecular formula of a substance from a given
model or diagram in these forms showing the atoms and
bonds in the molecule.
What is metals structure?
Metals consist of giant structures of atoms arranged in a regular
pattern
State the characteristics of metals
- The electrons in the outer shell of metal atoms are delocalised
- So they are free to move through the whole structure.
- The sharing of delocalised electrons gives rise to strong metallic bonds