Chemical Changes And Structure Flashcards
Metallic bonding
Li Be H
Na Mg Al
K Ca
Covalent network
B Si
Covalent molecule
C N O F
P S Cl
Monatomic
He Ne Ar
Properties of Metals
Good conductors of heat and electricity
Shiny
Malleable
Ductile
High melting points
Describe metals
Outer electrons can move easily from atom to atom. Delocalised electrons. Strong forces between the positive ions and delocalised electrons.
Properties of monatomic elements
Exist as individual atoms
Full outer energy levels
LDF’s are always present
Temporary dipole
Explain a temporary dipole
Continual movement of electrons in an atom which causes a temporary uneven distribution of charge at opposite sides of an atom, this means that one side is S+ and one side is slightly S-
What does having more electrons mean in terms of of LDF’s?
The LDFS are weak but with more electrons there is in the atom the bigger the LDFS
What is a covalent molecular bond?
It’s the mutual attraction of the nuclei for the shakers pair of electrons
What type of bonds are present and where in covalent molecular molecules?
Weak LDFS between molecules
Strong covalent bonds between atoms in the molecules
Properties of covalent network
Mon-metal, extremely high melting and boiling points
Silicon, carbon, boron
Explain diamonds properties
No delocalised electrons therefore it’s a non conductor of electricity, excellent conductor of heat. Hardest substance at room temp due to the closely packed atoms. 1 carbon bonds to 4 carbons
Explain the properties of carbon/graphite
Conducts electricity. Lead. 1 carbons bonds to 3 carbon cause the 4th carbon is delocalised therefore it conducts electricity
Explain the properties of silicon
Very high melting points, very hard, poor conductor of electricity. Semiconductor. Similar bonding to diamond. 1 carbon=4 carbon bonds
Explain the properties of boron
Similar bonding to carbon. 1carbon=3 carbon, 4th is delocalised. Stable covalent networks, very hard, high melting points
How are covalent bonds made?
They are formed when non-metal atoms shaired a pair of electrons.
How are the electrons shaired when in pure covalent?
They are shared equally and have the same electronegativity value
What does it mean when it has a permanent dipole?
It’s polar covalent, which means it has a small difference in electronegativity
What does it mean if it has ionic bonding?
Large difference in electronegativity. Also it’s the electrostatic force of attraction between positive and negative ions.
If a molecule had permanent-dipole-permanent-dipole bonding what bonding does it have?
Polar
How can you also tell if a molecule is polar or non-polar?
By looking at its structure
Explain hydrogen bonding properties and how it’s formed
Highly electronegative elements, F,N,O. Highly polar and have very strong p-d-p-d interactions. They are the strongest van der waals forces
how do you balance ion-electron equations?
- balance the number of elements
- add water to balance the oxygen
- add H to balance h atoms
- add electrons to balance the charge
oxidising agents tend to be more….
positive
reducing agents tend to become more…
negative
acidified peroxide is…
an oxidising agent as it accepts electrons and is reduced itself
acidified dichromate is…
an oxidising agent as it accepts electrons and reduces itself
carbon monoxide is…
a reducing agent as it accepts electrons and is reduced itself
Define the term first ionisation energy
The amount of energy to remove one mole of electrons from one mole of atoms in a gaseous state
Electronegativity across a period
Increases due to increased nuclear charge
Electronegativity down a group
Decreases due to the electrons being further away
Ionisation down a group
Decreases due to an increased electron screening effect
Ionisation energy across a period
Increases as you go across cause the increase in protons which means there is a stronger nuclear charge
