Topic 2-Bonding, Structure and the Properties of matter Flashcards
what is an ion
a charged particle that has gained or lost electrons to become stable
why do we not really see group 3,4.5 ions
as it requires a lot more energy for them to lose or gain electrons
how do ionic bonds form in terms of electron transfer
electrons are transferred making both atoms stable ions.the 2 ions have opposite charges and are attracted by electrostatic forces(ionic bond) which form an ionic compound
what does an electrostatic force do
-they attract protons and electrons within ions and atoms
-they attract oppositely charged ions
what does ionic bonding normally involve
a metal atom transferring 1 or more electron to a non metal atom to form 2 oppositely charged ions which are attracted to each other by electrostatic forces forming an ionic bond.this is called an ionic compound
what do ionic compounds involve
each electron being attracted to those oppositely charged ions around them forming a 3d regular lattice structure
list properties of ionic compounds
can conduct electricity-when aq or melted
have high melting and boiling points-ions are free to move about(charged particles)
what are the formulas for hydroxide and sulfate ions
oh- and so4 2-
why are brackets used-
to show that a ion like hydroxide needs 2
list common ionic compounds and their symbols
nitrate-no- 3
carbonate- co 2- 3
ammonium ion nh+ 4
what are displayed formulas downsides
they save time to draw complicated big models
dont show you anything about 3d shape of molecule
what are the substances covalent bonds can make
small molecular substances-with strong covalent bonds but weak imf-eg water/methane
-polymers-used to make plastic bags/t-shirts
also giant covalent structures like silicon dioxide/diamond or graphite
what are the properties of giant covalent structures
high melting and boiling points
apart from graphite cant conduct electrity
what is the main difference between simple molecular substances and giant
Covalent substances that only contain a few atoms are called
simple molecular substances.
On the other hand, covalent substances with millions of atoms are called giant covalent structures.
why are most simple molecules gases at room temp
In simple molecular substances, the individual molecules are held together by intermolecular forces that exist between the molecules.
These intermolecular forces are weak and so don’t require very much energy to break.
This means that they can be broken at relatively low temperatures. As a result most simple molecular substances exist in the gaseous state at room temperature.
why do halogens exist at different states at room temp
Chlorine is a gas at room temperature.
Bromine is a liquid at room temperature.
Iodine is a solid at room temperature and gives off purple fumes.
The reason they are in different states at room temperature is that they have different melting and boiling points. As you go down group 7, the atoms (and thus molecules) get bigger. This means there will be more intermolecular forces, and so more energy (and a higher temperature) will be required to break them.
what is a similarity between giant and simple molecular substances
they both cant conduct electricity
4 facts on giant covalent structures
Every atom is connected by strong covalent bonds
No weak intermolecular forces as there is only one structure
High melting and boiling points
Cannot conduct electricity (except graphite)
what are nano particles
tiny particles between 1-100nm long
what are the uses of nano particles
medecine
catalysts
electronics
deodrants
what is the difference in simple and giant molecular substances
giant have millions of atoms while simple have only a few
4 point summary on giant molecular structures
Every atom is connected by strong covalent bonds
No weak intermolecular forces as there is only one structure
High melting and boiling points
Cannot conduct electricity (except graphite
what are allotropes
different structural forms of the same element in the same physical state
how many carbon atoms are bonded in diamond
4
why can graphite conduct electric/heat
has 1 spare electron which becomes delocalised being able to conduct electricity and heat
how is graphite arranged
atoms are arranged into hexagons which together form large flat sheets which are placed on top of each other to form many layers
why is graphite slippery/soft
layers are free to slide over each other as there are no covalent bonds between them
There are only weak imf holding them together requiring less energy to break
Why is grapheme useful in electronics
Each atom donates an electron to a delocalised pool of electrons and therefore it can conduct electricity
What are tubes and spheres of graphite called
Fullerenes
What are the uses of fullerenes
Spheres
Drug delivery
Industrial catalysts
Nanotubes
In nanotechnology
Electronics
Tennis racket frames
When happens between outer shell electrons and positive atoms of a metal
They become positive ions as they lose the outer shell electrons which become delocalised allowing the metal to conduct electricity
How is a metal held together in a regular structure
The electrostatic forces of attraction between its positive ions and negative electrons hold it together
Wgat are some qualities of metals
Can conduct electricity and heat
Have high mp and bp
Malleable
What is an alloy
2 or more different elements
How can some alloys be much stronger than pure metals
The atoms of the elements used can be different sizes disrupting the regular arrangement of atoms so the layers can no longer slide
What is the diameter range of nano particles
1nm-100nm
What are the key features/uses of nano particles
Have High sa to vol ratio
Used as catalysts
Used in nano medicine
Silver nano particles have anti microbial properties so are used in surgical masks
Used in electrical circuits
What are risks using nano particles
New so long term effects pn our body are unknown
Eg in
Suncream where their high sa to vol ratio makes them more effective and have more skin coverage but may get into our skin and cells causing harm
In oceans they may be damaging environment as we don’t know what happens when they get in the sea
