Bonding Flashcards
What are the three main types of bonding ?
Covalent bonds
Metallic bonds
Ionic bonds
What is covalent bonds between?
Non-metals
What are metallic bonds between?
Metals
What are ionic bonds between ?
Compound containing metals and non-metals
What is the only group to exist as single atoms and do not bond ?
Noble gases
What do atom achieve when they bond ?
Full outer electron shell
What is a covalent bond?
The attraction between the two positive nuclei and a shared pair of electrons (negative)
What is a molecule?
A group of atoms held together by covalent bonds.
What are chemical bonds ?
Invisible forces of attraction between positive and negative charges that hold atoms together
What are the 2 types of covalent substances ?
Covalent molecular
Covalent network
What are covalent molecular structures like ?
Discrete and held together by weak intermolecular forces (called Van Der Waals force)
Why do covalent molecular substances have low melting and boiling points ?
Only weak Van Der Waals need to be broken
What do covalent network structures consist of ?
A giant lattice of atoms all covalently bonded to each other
Why do covalent network substances have high melting and boiling points?
Strong covalent bonds must be broken
Give 3 examples of covalent network?
Carbon diamond
Carbon graphite
Silicon dioxide
What is the difference between the melting point of a covalent network and a covalent molecular?
Covalent molecular : low mp/bp
Covalent network : high mp/bp
What is the difference in the type of bond broken to melt between a covalent network and a covalent molecular ?
Covalent molecular : intermolecular forces (weak Van Der Waals)
Covalent network : strong covalent bond
What condition can covalent molecules be at room temperature?
Solid
Liquid
Or gas
What condition are covalent networks at room temperature ?
Always solid
What are ionic bonds formed between?
Metals and nonmetals
How do ionic compounds form?
By transferring electron(s) from the metal to the nonmetal
When ionic compounds react, what happens to the metal atoms?
Loses electrons to become positively charged ions.
When ionic compounds react, what happens to the nonmetal atoms?
Gain electrons to become negatively charged ions.
What are the resulting ions considered as after an ionic compound has been formed?
The resulting ions are oppositely charged and attract each other
What is the definition for ionic bonding ?
The force of attraction between positive and negative ions.
Describe ionic bonds?
Very strong
When an ionic bond forms what do both ions gain?
A full outer electron shell
What structure do ionic compounds form?
A giant lattice of oppositely charged ions
Why do ionic substances have high melting and boiling points?
Strong ionic bonds must be broken to separate them
What condition are ionic substances in at room temperature?
Solid
What is the only compound which would appear to be ionic but isn’t ?
State what it is, it’s condition at room temperature, what is its actual bonding, how we know this?
Titanium (IV) chloride
Liquid at room temp
Covalent molecular substance
Low melting/boiling point
Describe the electrons on the outer shell of metal atoms ?
They are very loosely held and easily become delocalised.
What are delocalised electrons attached to?
Their own nucleus and neighbouring nuclei.
What is the definition for metallic bonding?
The force of attraction between positively charged ions and delocalised electrons.
What does delocalised mean?
Able to move freely
What is an electrical current?
A flow of charged particles (either electrons or ions)
When will a substance conduct electricity ?
When charged particles are free to move through the material
Describe the conductivity of covalent substances ?
Covalent substances (solid,liquid,solutions) do not conduct electricity since they are made up of molecules which are uncharged and there are no free charged particles
What is the only covalent substance which conducts electricity and why?
Carbon (graphite) conducts electricity because it contains free electrons.
Describe the conductivity of ionic substances and why?
Solid ionic substances do not conduct electricity because the ions are held tightly in an ionic lattice and are not free to move.
Ionic liquids(molten/in solution) will conduct electricity because ions are free to move
What will melting or dissolving an ionic substance do?
Break down the lattice and allow ions to move freely.
What is an electrolyte ?
An ionic liquid which conducts electricity.
Describe the conductivity of metal elements and why ?
Metal elements (solid/liquid) are conductors of electricity because they contain delocalised electrons which are free to move.
In terms of solubility in water, what do ionic compounds tend to be?
Soluble in water
In terms of solubility in water, what do covalent substances tend to be ?
Insoluble in water
What does electrolysis use electricity to do?
Break down ionic compounds
What does ‘lysis’ mean ?
To break/breaking
What ions move towards in terms of electrolysis?
The oppositely charged electrode
Why is a DC power supply used?
So that electrodes stay the same charge throughout and the products could be identified at each electrode.
What happens at the negative electrode during electrolysis ?
Positive ions (metals) gain electrons to become atoms.
How can we show metal atoms gaining electrons or nonmetals losing electrons?
Write as an ion-electron equation
Write the ion-electron equation for copper?
2+ -
Cu + 2e } Cu
Give the ion-electron equation for chlorine?
- -
2Cl } Cl + 2e
2
What must ion-electron equations be for nonmetals ?
Reversed
