Ch3 Chemical bonding Flashcards
What is chemical bonding
Attraction between atoms that allows the formation of chemical substances involving two or more atoms
What does ionic bonding occurs between
Metal and a non-metal
G1,2&3 - G6&7
What are the three ways we can test for ionic compounds
- Solubility.
- Melting point
- Electrical conductivity
Define an ionic bond
-Electrostatic attraction between oppositely charged ions involving a metal and a non-metal
What are some examples of ionic compounds and their uses
Sodium fluoride prevents tooth decay
Silver halides are used in photographic film
What structure do Ionic compounds form
Giant structures
Define covalent bonding
The electrostatic attraction between the shared pair of electrons (negative) and the nuclei (positive) on either side
What do covalent bonds occur between
Two non metals
Are covalent bonds solid liquid or gases
All three
E.g. graphite, water and carbon dioxide
Can covalent bonds conduct electricity
No because they share electrons so they can’t move
What are the three types of covalent bonds
- Single covalent bond where each atom she has one electron e.g. HCl
- Double bonds where each atom shares two electrons e.g. O
- triple bonds where each atom shares three electrons Eg N
When Atoms bond covalently, they tend to do so in a way that forms the maximum number
There are two types of covalent compounds, what are they
- Simple structure
- Giant covalent lattice
Describe a simple molecular structure
- Consists of simple molecules (two or more atoms bonded together) which are attracted together through INTERMOLECULAR FORCES
- tends to be liquids and gases and have low melting points because of the weak bonds
- Do not conduct electricity
Describe giant covalent structures
- Mainly solids, crystalline and hard
- No intermolecular forces in compound (exception: graphite) only strong covalent bonds
- Result is high melting point, high boiling point
- Do not conduct electricity
Explain about the electrons in graphite
The fourth electron falls between the layers meaning it can conduct electricity because it is delocalised and free
Between what does metallic bonding occur
Metals
G1,2,3& transition metals
Explain what happens during metallic bonding
- The metal atom loses outer shell electrons to form positive metal ion
- Electrons are delocalised into the space between the positive metal ion is common known as’ sea of delocalised electrons’
- Delocalised electrons are free to move so they can conduct electricity and heat
- Metallic bonds is the electrostatic attraction between the negative sea of delocalised electrons and the positive metal ion
What is an alloy
A mixture of two or more metals
E.g. brass = copper +zinc
-Steel = iron + zinc +!carbon
What are the physical properties of metallic bonding
- Conduct electricity and heat
- Have high melting and boiling points
- Hard and dense
- Malleable (can be hammered into shape)
- ductile (can be drawn out in wires
Finish the sentence
In ionic bonding, the higher the number of charges (+, 2+,3+,4+…)…
The stronger the attractions
What are the physical properties of ionic compounds
- The consequence is bonding is very strong which results in:
- hard crystalline solid’s e.g. salts
- high melting points
- conduction Malton, conducting a solution, does not conduct when solid
What are the properties of compounds with giant ionic structures
- Made of crystals
- Usually have high melting points
- Often soluble in water
- Conduct electricity when molten or dissolved in water, but not when solid
What are intermolecular forces
Without them, nothing could hold together as a solid or a liquid.
They vary in strengths, but not as strong as covalent or ionic bonds
When something melts or boils, what is being broken?
The intermolecular forces-Not covalent bonds
