Topic 2 Flashcards
What is ionic bonding?
Ionic bonding is a strong electrostatically charged attraction between a metal and a non-metal where electrons are lost and gained forming ions
Ionic Bond between sodium and chlorine to produce a 2 ions in a ionic bond
What effects the strength of ionic bonding?
Ionic Charge
- The more electrons being lost or gained
- Increases bond strength
Ionic Radius
- The smaller the ionic radius the smaller the distance of the electrons to the nucleus
- Increasing bond strength
How are ions formed (cations and anions)?
Atom loose / gain electron ⇒ Ions
Cation = Positive ion (Electron lost)
Anion = Negative ion (Electrons gained)
What are isoelectric ions?
Isoelectric ions are ions that have the same electronic configuration but different amounts of protons
Example
N^3,O^2-,F^{-},Na^{+},Mg^{2+},Al^{3+}
What are the trends in ionic radii down a group?
As you go down the group ionic radii increases because
- The amount of electron shielding increases
- Increasing the size of the overall ion
- Decrease in nuclear charge
- Meaning the ionic radii increases
What are the trends in ionic radii in isoelectric ions?
As you go along a group of isoelectric ions the ionic radius decreases because:
- The number of protons increase
- The nuclear charge increases
- Pulling the electrons closer to the nucleus
- Decreasing ion size
- Decreasing ionic radii
What are the properties of ionic compounds?
- Strong bonds (High Energy to Break)
- Soluble in water (polar substances) but not in non polar substances (Ions pulled apart by polar molecules)
- Electrical conductor in aqueous and free to carry a charge (Not in fixed position like solid)
What is the migration of ions?
Electrolysed Copper(II) Chromate(VI) on wet filter paper
Green Copper Chromate separates as
- Blue copper cations move to the negative anode
- Yellow chromate anion move to the positive cathode
What is covalent bonding?
A strong electrostatic attraction between two positive nuclei and the shared electrons in a bond between a non-metal and a metal
What is electron repulsion
- The shape of a molecule or ion is caused by repulsion between the pairs of electron surrounding the central atom
- The electron pairs arrange themselves in a way where there is the maximum distance away from each other
- Keeping repulsion between them at a minimum
- Lone pairs have stronger repulsion
What are some examples of the bond angles in molecules and ions?
What is electronegativity?
Electronegativity is the ability of an atom to attract incoming electrons in a covalent bond
What is a dipole?
A separation of charge due to the drift of bonded electrons towards the more electronegative element
What is does it mean a bond is polar?
- Where the difference in electronegativity
- Is enough to cause a uneven distribution of electrons (a dipole) towards the more electronegative element
What does it mean if a bond is non-polar?
- Where the electronegativity difference between the bonded elements is not large enough
- Meaning a uneven distribution of electrons isn’t created
What does it mean if a molecule is polar?
- If a molecule is polar then there is no symmetry in polar bond
- As well as containing any polar bonds
What does it mean if a molecule is non-polar?
- Contains no polar bonds
- Contains polar but they are polyatomic meaning the molecule is symmetrical meaning dipole cancel each other out
What is the structure of metallic bonding?
- Lattice of positively charged ions
- Surrounded by a sea of delocalised electrons
- Strong electrostatic forces of attraction between the oppositely charged particles
What is the structure of diamond?
- Each carbon atom has four sigma bonds
- Strong C-C bonds lead to high melting points
- Giant 3D tetrahedral arrangement
- Bond angles of 109
What is the structure of graphite?
- Each carbon bonded to 3 sigma bonds forming interlocking rings
- Strong C-C bonds lead to high melting points
- Fourth electron on each carbon is delocalised in the p-orbital and moves between layers making graphite conductive
- Used as a lubricant as layers can slide over each other
What are some examples of simple molecular lattices?
- Iodine + Ice
- Iodine has a face centred cubic structure
- Held together by London forces
