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Bell Work. What charges will each of the following have as ions?. Br S Mg Ba I Al Sr N P B. Physical Science – Lecture 39. Bonding. Octet Rule. All elements want 8 electrons in their outer shell. They want 8 valence electrons to be complete.
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Bell Work • What charges will each of the following have as ions? Br S Mg Ba I Al Sr N P B
Physical Science – Lecture 39 Bonding
Octet Rule • All elements want 8 electrons in their outer shell. • They want 8 valence electrons to be complete. • Elements want valence electrons equal to noble gases (group 8A) • Only exception – Hydrogen and Helium only want 2.
Becoming a Noble Gas • Elements can lose or gain electrons to become “noble like”. • Loss of electrons = cation (+ charge) • Gain of electrons = anion (- charge)
Cations • Elements lose electrons to become positive • Positive charge comes from an abundance of protons. • For every electron lost, elements becomes +1.
Anions • Elements gain electrons to become negative • Negative charge comes from an abundance of electrons. • For every electron gained, elements becomes -1.
Two types of Bonding - 1 • Covalent – between two non-metals. They share electrons. • Two non-metals will share electrons to make them both think that they have a full outer shell.
Forming Covalent Compounds • When elements covalently bond, they are given special names to designate how many of each element is present.
Covalent Bonding • Formed between two non-metals. • Neither atom is "strong" enough to steal electrons from the other. • Instead, they share their electrons from outer molecular orbit with others to feel complete (8).
Covalent Bonding • Elements can form single bonds, double bonds, or triple bonds with other elements. • Bonds are represented with line drawn between two elements.
Single Bond • Two electrons are shared between elements
Double Bond • Four electrons are shared between elements
Triple Bond • Six electrons are shared between elements
Counting to 8 • Each pair of electrons (lone pair) counts as 2 electrons toward the total of 8 for the element they are attached to. • Each covalent bond (line) counts as 2 electrons for each element they are attached to. • Everyone still wants 8.
Types of Bonding - 2 • Ionic – between a metal and a non-metal or a cation and an anion. They steal or give away electrons to each other. • A metal will give its electrons to a non-metal to have a completed octet in the octet below its valence shell (becoming a cation). • A non-metal will take electrons from a metal to fulfill its outer valence shell (becoming an anion).
Lone Pairs • Electrons not involved in the bond are called “lone pairs”. • Lone pairs consist of two electrons.
Ionic Bonding • Ionic bond - type of bond formed between cations and anions. • Mostly formed between metals and non-metals. • Non-metals are more electronegative and steal the metals electrons.
Ionic Bonding • Na does not have 8 electrons in its outer shell, it has none. • It gave away electrons. It did not share.
Ionic Bonding • Metals NEVER keep their electrons! • They always give them away to non-metals. • They NEVER share!
Forming Ionic Compounds • Ionic compounds come from ions. • The charges cancel out • The cation (positive charged element) is written first in the formula. • The anion is always written second.
Examples • Ca2+ and SO42- • Br- and Na+ • K+ and O2-
Can 3 Cl form a Covalent bond with P? • What type of bond will they form? • Do they have enough electrons to make them each feel like they have 8?
