Structure and Bonding
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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What general properties do metals have
Conduct electricity Shiny Malleable
What general properties do most non-metals have
Don’t conduct heat + electricity (insulators) Weak (brittle) Dull colour
What type of elements are involved in Ionic bonding
Metal + non-metal
What type of elements are involved in covalent bonding
Non-metal + non-metal
What type of elements are involved in metallic bonding
Metal + Metal
Covalent bonds =……….
Strong
Describe simple molecular bonds
Non metal + non metal Strong covalent bonds within molecules Weak intermolecular forces that requires little energy to break
What is a covalent bond
The electrostatic attraction between the positive nuclei and the shared pair of electrons
Are covalent binds weak or strong
They’re strong because of the strong electrostatic attraction
Do simple molecular structures conduct electricity
No - they don’t have a sea of delocalised electrons It’s an insulator
Why does the melting points of a substance with simple molecular bonds increase
As the molecules get bigger, there are more intermolecular forces, so more energy required to overcome them
Describe giant covalent structures
Strong covalent bonds
Do giant covalent structures conduct electricity
No, they don’t have a sea of delocalised electrons, except GRAPHITE!
Why does diamond have a high melting point
Because of it’s giant covalent structure With many strong covalent bonds Which require a lot of energy to overcome
Describe a Giant Ionic structure
Strong ionic bonds Positive cations Negative anions Giant 3D lattice
How and why do ions form
Metal atoms loose electrons to become positive ions with full outer shells Non-metal atoms gain electrons to become negative ions with full outer shells
Describe the structure of ionic materials
Giant 3D lattice
Why do solid ionic substances not conduct electricity
No delocalised electrons and the ions can’t move
When do ionic substances conduct electricity
When in a liquid state - ions can move
Why do ionic compounds have high melting points
Strong electrostatic forces between oppositely charged ions that require a lot of energy to break
Why does MgO have a higher melting point than NaCl
Magnesium oxide is 2+ 1- and NaCl is 1+ 1-. So MgO has a higher attraction so more energy is needed to overcome this
Describe giant metallic structures
Strong electrostatic attraction between ions Sea of delocalised electrons Layers of atoms which can slide over each other Malleable Ductile
Describe the structure of metals
Layers of positive cations surrounded by a sea of delocalised electrons
What is metallic bonding
The strong electrostatic attraction between positive metal ions and a sea of delocalised electrons