Bonding A1 Flashcards
Module 2
What is the definition of a metallic bond?
The strong electrostatic attraction between cations and delocalised electrons.
How does metal ion charge and ionic radius affect the strength of metallic bonding?
The higher the charge, the stronger the bond.
The larger the ionic radius, the weaker the bond.
Describe the structure of metals.
Cations are fixed in position - maintaining structure and shape of the metal.
Each atom donates its outer shell of electrons to a shared pool of electrons which are delocalised.
Delocalised electrons are mobile so move throughout structure (can carry charge).
What is the definition of an ionic bond?
The strong electrostatic attraction between positive and negative ions. (between metal and non-metal)
How does ion charge and ionic radius affect the strength of ionic bonding?
How does strength of ionic bonding affect the m.p/b.p of an ionic compound?
The higher the charge, the stronger the bond.
The larger the ionic radius, the weaker the bond (because the charge is spread over a large surface area).
The stronger the bond, the higher the mp/b.p of an ionic compound.
What do ionic compounds form?
Giant Ionic Lattices
- each ion is surrounded by oppositely charged ions.
What is the definition of a covalent bond?
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
What is a lone pair of electrons?
An electron pair not involved in bonding.
What is the average bond enthalpy?
A measurement of bond strength.
In a dot and cross diagram, does there have to be 8 electrons in the outer shell? (Octet Rule)
No there are exceptions - it can be more or less.
Elements in period 3 such as P, S and Cl can hold up to 18 electrons in their outer shell so they can form more bonds.
What happens in a dative covalent compound?
One element gives both electrons to the bond.
What does the electron repulsion theory state?
Electron pairs repel each other to be as far apart as possible.
Put in order the amount of repulsion in terms of electron pairs from greatest to least.
2 lone pairs (repel most)
1 lone pair, one bonded pair
2 bonded pairs (repel least)
What is electronegativity?
The ability of an atom to attract a bonding pair of electrons.
What happens to electronegativity as you go down the group? Why?
It decreases because:
- more shells, so more shielding
- atomic radius increases (outer shell further from the nucleus)
- so valence electrons less attracted to the nucleus.