Atomic Structure and Bonding Flashcards
What is an isotope?
Isotopes are variations of an element with the same number of protons but a different number of neutrons.
Relative Isotopic Mass
The mass of one isotope compared to one twelfth of the mass of one atom of C12.
Relative Atomic Mass
The average mass of one atom compared to one twelfth of the mass of one atom of C12.
Relative Molecular Mass
The average mass of a molecule compared to one twelfth of the mass of one atom of C12.
Cl exists in two isotopes 35 and 37. How many peaks would there be in a mass spectra for Cl2?
3 peaks.
35 + 35
35 + 37
37 + 37
What are spectator ions?
Ions that are not changing state, nor changing oxidation number.
What is ionic bonding?
Electrostatic forces of attraction between oppositely charged ions.
When does the strength of ionic bonding increase?
Regarding Atomic Radius, Charge and Charge Density
Atomic Radius Decrease
Increase Charge
Increase Charge Density
Typical Properties of Ionic Compounds?
- Usually soluble in aqueous solvents
- None conductor of electricity when solid however molten ions are free to move and carry charge
- Crystalline solids
- High Melting Points
What is covalent bonding?
The strong electrostatic forces of attraction between a shared pair of electrons and the nuclei of the bonded atoms.
Dative bond
Where a pair of electrons is donated from one atom to another.
Which two compounds are giant covalent?
C and SiO2
What is electronegativity?
The relative tendency of an atom in a covalent bond in a molecule to attract electrons in a covalent bond to itself.
How does electronegativity change as you go down the group?
Decrease
- Increased Atomic Radius
- More Shielding
- Same Charge
How does electronegativity change across the period?
Increase
- Increased Charge
- Decreased Atomic Radius
- Same Shielding
In spin diagrams, what do the arrows going in different directions represent?
The different spins of the electrons in the orbital
What are shells made up of?
Atomic Orbitals
What is an atomic orbital?
Regions around the nucleus that can hold up to two electrons with opposite spins.
A region of space where there is a high probability of finding an electron.
What shape are s orbitals?
How many of these are there in a shell?
How many electrons can it hold?
Spherical
1 Orbital
2 Electrons
What shape are p orbitals?
How many of these are there in a shell?
How many electrons can it hold?
Dumbell
3 Orbitals
6 Electrons
What shape are d orbitals?
How many of these are there in a shell?
How many electrons can it hold?
Four Leaf Clover
5 Orbitals
10 Electrons
What shape are f orbitals?
How many of these are there in a shell?
How many electrons can it hold?
Tetrahedral
7 Orbitals
14 Electrons
Why do electrons have a property called opposite spin?
The two electrons in an orbital must have opposite spins as if helps to counteract the repulsion between the negative charges of the two electrons. They have to reach the point of minimum repulsion.
Draw NH4+.
Compare with diagram.
Draw SF6.
Compare with diagram. Electron rich.
Sulfur hexafluoride can be used to make your voice sound deeper.
Draw BCl3.
Compare with diagram. Electron deficient.
Shape of Molecule: Linear
No. Bonded Pairs:
No. Lone Pairs
Bond Angle:
2 Bonded Pairs
0 Lone Pairs
180
Shape of Molecule: Trigonal Planar
No. Bonded Pairs:
No. Lone Pairs
Bond Angle:
3 Bonded Pairs
0 Lone Pairs
120
Shape of Molecule: Tetrahedral
No. Bonded Pairs:
No. Lone Pairs
Bond Angle:
4 Bonded Pairs
0 Lone Pairs
109.5
Shape of Molecule: Trigonal Pyramidal
No. Bonded Pairs:
No. Lone Pairs
Bond Angle:
3 Bonded Pairs
1 Lone Pair
107
Shape of Molecule: Bent
No. Bonded Pairs:
No. Lone Pairs
Bond Angle:
2 Bonded Pairs
2 Lone Pairs
104.5
Shape of Molecule: Octahedral
No. Bonded Pairs:
No. Lone Pairs
Bond Angle:
6 Bonded Pairs
0 Lone Pairs
90
Why is CO2 a linear shape?
Electron pairs repel to the point of minimum repulsion.
CO2 has 2 bonded pairs and 0 lone pairs.
No lone pairs so electron pairs repel equally.
Therefore the CO2 molecule is linear with a 180 degree bond angle.
Why is PF3 a trigonal pyramidal shape?
Electron pairs repel to a point of minimum repulsion.
There are 3 bonded pairs and 1 lone pair.
Lone pairs repel more than bonded pairs.
Therefore the PF3 molecule is trigonal pyramidal with a 107 degree bond angle.
How does a permanent dipole-dipole (polar covalent) bond form>
When the elements in the covalent bond’s electronegativities differ by > 0.5. IT therefore has an unequal distribution of electrons in the bond and produces a charge separation.
What is the link between symmetric molecules and electronegativity?
A symmetric molecules (all bonds identical and no lone pairs) it will not be polar even if individual bonds within the molecules are polar as they cancel out. There is no net dipole movement, the molecules is none-polar.
A very large electronegativity difference will be… > 2.0.
Ionic Bonding!
What is a mole?
The amount of substance that contains the same number of particles as 12g of C12
What are the properties of metals and why?
- High mp + bp due to strong EFAs
- Malleable/ Ductile as ions can slide over each other
- Good conductor of electricity in solid or molten states