Chapter 4 ~chemical Bonding Flashcards
Definitions and key elements
What are the 3 types of intramolecular forces?
- Ionic bonds
- Covalent bonds
- Metallic bonds
Intramolecular definition :
Forces that hold atoms together within a molecule
Definition of intermolecular forces :
The weak forces that exist between molecules
The 3 types of intermolecular forces
- Van Der Waal’s forces (also called dispersion, London, temporary dipole-induced dipole forces)
- Permanent dipole-dipole forces
- Hydrogen bonds
How are ions formed?
When atoms gain or lose electrons
Definition of an ionic bond
°the electrostatic attraction between oppositely charged ions (happens between non-metals and metals)
Definition of electrovalent
°it is another name for an ionic bond which is the electrostatic attraction between oppositely charged ions
Definition of dot and cross diagrams
A diagram showing the arrangement of the outer shell electrons in an ionic or covalent element or compound. The electrons are shown as dots or crosses to show their origin
Definition of a covalent bond
A bond formed by the sharing of pairs of electrons between 2 atoms (non metal and non metal)
Definition of double covalent bond plus 3 examples
°atoms sharing 2 pairs of electrons
Examples : oxygen molecule, carbon dioxide (between the oxygen and carbon atom) and ethene (between the 2 carbons)
Definition and one example of a triple covalent bond
° when atoms bond together by sharing 3 pairs of electrons
Examples: nitrogen molecule
Definition of a co-ordinate bond or dative covalent bond and 2 examples
°a covalent bond in which both electrons in the bond come from the same atom
Or
It is formed when 1 atom provides both the electrons needed for a covalent bond
Examples :
- Ammonium ion NH4+ (the hydrogen is electron deficient)
- Al2Cl6 (the AlCl3 is electron deficient)
For a dative covalent bond we need two things :
- 1 atom having a line pair or electrons
2. A 2nd atom having an unfilled orbital to accept the lone pair (an electron deficient compound)
Electron deficient compound definition and example
° a noble gas configuration is not achieved and the compound too little electrons
Example : boron trifluoride BF3 (only has 6 e-)
What is an expanded octet and an example of one
° too many electrons to achieve a gas configuration
Example: sulfur hexaflouride SF6 (has 12 e-)
Aluminum chloride at high and low temperatures
High temperature : AlCl3 (electron deficient - still needs 2e-)
Low temperature : Al2Cl6 (the AlCl3 molecules bond bec of lone pairs of 2 Cl atoms & form a dative covalent bond with Al atoms
What is bond energy/ bond enthalpy ?
°the energy required to break 1 mole of a particular (given) bond in 1 mole of gaseous molecules
What is bond length?
The average distance between nuclei of 2 bonded atoms in a molecule
Why are double bonds shorter than single bonds?
Bec double bonds have a greater quantity of negative charge between the 2 atomic nuclei.
The greater force of attraction between the e-s and the nuclei pulls the atoms closer together.
Stronger bond
3 things that determine chemical reactivity
- Bond strength
- Polarity
- Whether bond is sigma or pi bond
A reaction on happens when…
A successful collision 💥 occurs with enough energy to break bonds in either or both molecules
Why is nitrogen unreactive?
It has a triple bond that requires a lot of energy to break the nitrogen atoms apart
What is the relationship between bond energy and bond length
Inversely proportional. As bond length decreases bond strength (bond energy) increase
Electron repulsion theory
× E-s are all negative and therefore repel one another
× The repulsion forces the pairs of e-s apart until their repulsive forces are minimized
×order of repulsion:
Lone pair - lone pair (most repulsion) >lone pair - bond pair >bond pair - bond pair (least)