BIOL107 Lecture Notes - Lecture 2: Valence Electron, Covalent Bond, Ionic Bonding

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL107
• Professor: Martin Srayko

Document Summary

Of the 92 elements known, about are required for organisms to survive. C, h, o, p, s, n these elements make up >965 of living matter. The discrete shells that electrons can occupy have a specific capacity. The closest shell can only hold 2 electrons. The second shell can hold 8 electrons: 1st shell: 1s orbital, 2 electrons, 2nd shell: 2s, 2p, 2p, 2p orbitals, 8 electrons. The properties of the atom are determined primarily by the number of electrons in the outermost shell (valence electrons). Atoms with the same number of valence electrons behave similarl(cid:455) i(cid:374) (cid:272)he(cid:373)i(cid:272)al rea(cid:272)tio(cid:374)s. a(cid:374) ato(cid:373) (cid:449)ith a (cid:862)full(cid:863) (cid:448)ale(cid:374)(cid:272)e shell (cid:449)itll (cid:271)e unreactive (inert) Defines the number of protons in that particular element. Because electrons are negatively charged, when an element is in its neutral state, it will have the same number of protons as electrons. Note: every atom of boron contains 5 protons. Sharing of a pair of valence electrons by two atoms.