UNIT 1 - BONDING Flashcards
WHAT ARE IONIC BONDS ?
Bonds between metals and non-metals
HOW ARE IONIC BONDS FORMED ?
METALS LOSE ELECTRONS AND NON-METALS LOSE ELECTRONS IN ORDER TO ACHIEVE A FULL OUTER SHELL OF ELECTRONS
WHAT ARE THE PROPERTIES OF IONIC COMPOUNDS ?
HIGH MELTING AND BOILING POINT
BRITTLE
CONDUCT WHEN MOLTEN
SOLUBLE IN WATER
WHY DO IONIC COMPOUNDS HAVE HIGH MELTING AND BOILING POINTS ?
A lot of heat energy is required to break the strong ionic bonds / electrostatic forces between ions
WHY ARE IONIC COMPOUNDS BRITTLE ?
When force is applied to an ionic crystal, the layers shift bringing ions of the same charge together they repel causing the crystal to shatter
WHY DO IONIC COMPOUNDS CONDUCT WHEN MOLTEN ?
In a solid ions cannot move so cannot carry electricity
When molten or dissolved ions move to carry current
WHY ARE IONIC COMPOUNDS SOLUBLE IN WATER ?
Water molecules are slightly charged and so are able to break apart ions in ionic lattice
HOW ARE COVALENT BONDS FORMED ?
Electrons are shared between non-metals to complete a full outer shell
WHAT IS BONDED IN A COVALENT BOND ?
Non-metals
PROPERTIES OF COVALENT BONDS ?
LOW MELTING AND BOILING POINT
POOR CONDUCTORS
WHY DO COVALENT BONDS HAVE A LOW MELTING AND BOILING POINT ?
Covalent bonds are strong but the intermolecular forces are weak, meaning they can be broken with little heat energy
WHY ARE COVALENT COMPOUNDS POOR CONDUCTORS ?
They cannot conduct as they have no mobile charged particles
WHAT IS THE STRUCTURE OF DIAMOND ?
4 (c-c) bonds, no free electrons
WHAT ARE THE PROPERTIES OF DIAMOND ?
HIGH MELTING AND BOILING POINT
STRONG
ELECTRIC INSULATOR
WHY DOES DIAMOND HAVE A HIGH MELTING AND BOILING POINT ?
Each carbon forms 4 (c-c) bonds with strong covalent bonds which require high energy to break
NAME THREE CARBON ALLOTROPES
CARBON
GRAPHITE
GRAPHENE
HOW IS GRAPHITE STRUCTURED ?
Each carbon forms 3 (c-c) bonds
Free electrons between layers
Structured in layers
Hexagonal pattern
WHAT ARE THE PROPERTIES OF GRAPHITE ?
HIGH MELTING POINT
SLIPPERY
GOOD CONDUCTOR
WHY IS GRAPHITE SLIPPERY
Layers are strong but layers are held together by weak intermolecular forces
Layers slide over one another when pressure is applied
WHY IS GRAPHITE A GOOD CONDUCTOR ?
Delocalised electrons between layers can carry electrical current
HOW IS GRAPHENE STRUCTURED ?
A single layer of carbon atoms
3 (c-c) bonds + free electrons
WHAT ARE THE PROPERTIES OF GRAPHENE ?
STRONG
BEST KNOWN CONDUCTOR
WHAT ARE NANOTUBES MADE FROM ?
Graphene rolled into a tube of carbon atoms
Delocalised electrons inside
WHAT ARE THE PROPERTIES OF NANOTUBES ?
STRONG
BEST KNOWN CONDUCTOR
SLIPPERY - Tubes of electrons slide over eachother easily
WHAT IS BUCKMINSTER FULLERENE
Carbon Cages
3 (c-c) bonds
The fourth delocalised electron is in the middle
Used in drug delivery
HOW ARE METALLIC BONDS FORMED ?
In solid metals, metal atoms lose their outer shell of electrons
These electrons become delocalised and move freely around the lattice
Metal is held together by the strong electrostatic attractions between metal ions (+) and electrons (-)
WHAT ARE THE PROPERTIES OF METALS ?
MALLEABLE
DUCTILE
SHINY
STRONG AND INSOLUBLE IN WATER
GOOD CONDUCTOR
HIGH MELTING AND BOILING POINT
WHY ARE METALS MALLEABLE AND DUCTILE ?
Metals can be hammered as electrons move with the metal ions keeping the bonds intact as layers move.
WHY ARE METALS GOOD CONDUCTORS ?
Free electrons can carry current
WHY DO METALS HAVE A HIGH MELTING AND BOILING POINT ?
Lots of heat energy is required to break the the strong metallic bonds between metal ions and delocalised electrons.
NAME FIVE SMART MATERIALS
HYDROGELS
SHAPE MEMORY ALLOYS
SHAPE MEMORY POLYMERS
PHOTOCHROMIC PIGMENTS
THERMOCHROMIC PIGMENTS
WHAT IS A SMART MATERIAL ?
Smart materials have unique properties that are triggered by certain environmental conditions
WHAT ARE PHOTOCHROMIC PIGMENTS ?
Pigments that change colour depending on light intensity
i.e. sunglasses
WHAT ARE THERMOCHROMIC PIGMENTS ?
Pigments that change colour depending on the temperature
i.e. baby spoons and novelty mugs
WHAT IS A SHAPE MEMORY POLYMER ?
A plastic that returns to its original shape upon heating
i.e. gum shields and car bumpers
WHAT IS A SHAPE MEMORY ALLOY ?
An alloy that returns to its original shape upon heating
i.e. braces wires
WHAT IS A HYDROGEL ?
A superabsorbant polymer that can absorb 1000x its own volume in water
i.e. nappies
NAME TWO EXAMPLES OF NANOPARTICLES ?
SILVER NANOPARTICLES
TITANIUM DIOXIDE
WHAT ARE SILVER NANOPARTICLES USED FOR ?
Anti-viral, bacterial and fungal
Used in cleaning surgical equipment and coating fridges to stop odour
WHAT ARE TITANIUM DIOXIDE NANOPARTICLES USED FOR ?
They are transparent and repel water and UV rays
Used in transparent sunscreens and self-cleaning windows
WHAT ARE THE ISSUES LINKED TO NANOPARTICLES ?
Nanoparticles are so small that they can be inhaled or pass straight through the skin into the blood
We do not know the long term affects of these particles on our health.
