CHEM1201 Lecture Notes - Lecture 8: Nonmetal, Electron Configuration, Valence Electron
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Ionisation energy and electron affinity
Ionisation – removing an electron
Affinity – adding an electron
Ionisation energy of an atom:
- The minimum energy required to remove an electron from the atom in the gaseous
state
- Na(g) + ionisation energy → Na+(g) + e-
- Decreases down a group
- Increases across a group
Electron affinity:
- Measure of the energy released when an electron is added to a gaseous atom
- X(g) + e- → X- + energy
- Decreases going down a group
- Generally increases across a period
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Document Summary
The minimum energy required to remove an electron from the atom in the gaseous state. Measure of the energy released when an electron is added to a gaseous atom. X(g) + e- x- + energy. Ionic bonds: electrostatic interactions between ions of opposite charge, metal cations, non-metal anions. Cocalent bonds: sharing of electrons between two atoms, non-metals, polar/non-polar (depending on electron distribution) Oxygen electronic configuration is 1s22s22p4 6 valence electrons. Atoms bond because bonding results in a more stable electron configuration: more stable = lower potential energy. Atoms bond together by either transferring or sharing electrons. Usually, this results in all atoms obtaining an outer shell with eight electrons: octet rule, there are some exceptions to this rule: helium. The lewis structure of helium contains two paired dots (a duet) For helium and hydrogen, a duet represents a stable electron configuration.