Bonding Flashcards
Why do all elements want full outer shells?
Means they are stable in electron configuration and don’t react easily.
What’s ionic bonding?
Atom loses 1 or more electrons and donates it to an atom of a different element.
What’s electrostatic attraction?
Opposite charges on ions holding two ions together.
Diagram for ionic bonding?
Dot and cross diagrams in square brackets for metal and non-metal bond.
Ionic compound properties?
Hard
Brittle
High melting points
Conduct electricity when dissolved in water.
What is a covalent bond?
Electron shared between two atoms of non-metal elements.
Define Dative coordinative covalent bonding.
When covalent molecules both share electrons from one atom.
What’s a triple bond?
Three pairs of electrons are shared.
What’s bond length and it’s features?
Distance between atoms nuclei on a bond
Shorter bond length = stronger bond
Single bonds are longer than double bonds which are longer than triple bonds.
Define lone pairs.
Pairs of electrons in outer shell that haven’t bonded.
Covalent compound properties?
More flammable that ionic compounds.
Don’t conduct electricity when dissolved in water.
Most have low melting and boiling points.
Define Valence electron.
Electron in atoms outer shell that can participate in forming bonds with other atoms.
Point of electron pair repulsion theory?
Use compounds number of Valence electrons to predict it’s 3D-shape.
Define bonding pair.
Shared pair of electrons.
Define lone pair.
Pair of electrons not shared between two atoms.
VSEPR method and rules.
Valence/shell/electron/pair/repulsion
Rules:
- Identify central atom
- Count it’s Valence electrons
- Add one electron for each bonding atom
- Add/Subtract electrons for the charge.
- Divide total by 2 to find number of electron pairs.
- Subtract number of lone pairs if there are any.
- Use this number to predict shape.
What’s the Lewis diagram?
Only uses dots to represent electrons to avoid possibility of • and X being seen as different things.
So differs to dot and cross diagrams.
What’s the octet rule?
- When non-metals form molecules, they share electrons in outermost shell.
- Achieves stability as they can have 8 electrons in outermost shell.
- So helps us predict how elements will bond.
What are covalent bonds represented as?
- = 1 covalent bond.
== 2 covalent bonds
Three horizontal lines = 3 covalent bonds
About triple bonds.
Firm between 2 atoms that contribute 3 electrons each.
So 6 electrons shared.
Triple covalent bonds represented as a triple horizontal line.
Electron pair number rule.
Single covalent bond = 1 shared electron pair.
Double covalent bond = 4 electrons so 2 shared pairs.
Triple covalent bond = 6 electrons so 3 shared pairs.
True or false? Covalent bonding is always electron pairs?
True.
What are the shapes based on electron pairs?
2 pairs - linear 3 pairs - trigonal planar 4 pairs - tetrahedral 5 pairs - trigonal bipyramidal 6 pairs - Octahedral
What directions to wedges, lines and dots go in covalent structures?
Wedges - towards you.
Lines - sideways
Dots - away from you.
What’s the angles rule.
- In tetrahedrals their angle is lower.
- Due to repulsion from lone pair
- Repulsion between lone pair and bonding pair is greater than repulsion between 2 bonding pairs.
- So bonding pairs are closer together as a result.
Repulsion scale between pairs in covalent bonding?
(Most repulsion) Lone pair - lone pair Lone pair - bonding pair Bonding pair - bonding pair (Weakest repulsion)
