Chapter 5- Bonding Flashcards
When are ionic bonds normally formed?
When two elements with very different electronegativities form a compound. The difference in electronegativity causes the transfer of electrons, to make one species positive and the other negative.
What is meant by the term ‘covalent bond’?
A chemical bond in which two non-metal atoms share one or more pairs of electrons
What’s the main difference between covalent compounds and ionic compounds?
Covalent compounds are non-metals, with mainly similar electronegativities. Ionic compounds are formed with metals and non-metals, which means the electronegativities are very different.
State the Valence Shell Electron Pair Repulsion Theory
The VSEPR theory states that molecules will achieve a geometry that minimises the repulsion between electron-pairs
Which has a greater impact on the geometry of a molecule: bonded electron pairs or lone pairs?
Lone pairs of electrons
What results in a polar covalent bond?
The uneven sharing of electrons in the bond. This is due to one element being more electronegative, so it has a tendency to attract a shared pair of electrons towards itself.
Describe the trend in electronagativities in the periodic table
It increases up a group, and as you go left to right. Florine is the most electronegative element
What do Lewis structures show?
They show the distribution of valence electrons within a molecule, including bonding electrons
How many pairs of electrons are found in single covalent bonds?
1 pair of electrons
How many pairs of electrons are found in double covalent bonds?
2 pairs of electrons
How many pairs of electrons are found in triple covalent bonds?
3 pairs of electrons
Define the term ‘resonance structure’
There are cases where two or more energetically equivalent Lewis structures for a molecules can be drawn that only differ in the position of one electron pair
What is the shape of the molecule and the electrons that has 2 sets of electron pairs?
Electron geometry: Linear
Molecular geometry: Linear
What is the shape of the molecule and the electrons that has 3 sets of electron pairs?
Electron geometry: Trigonal planar
Molecular geometry: Trigonal planar (0 lone pairs), bent shape (1 lone pair)
What is the shape of the molecule and the electrons that has 4 sets of electron pairs?
Electron geometry: Tetrahedral
Molecular geometry: Tetrahedral (0 lone pairs), trigonal pyramidal (1 lone pairs), bent shape (2 lone pair)
