Ionic and Covalent Bonding 1. Bonding Atoms with unfilled valence shells are considered unstable....
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Transcript of Ionic and Covalent Bonding 1. Bonding Atoms with unfilled valence shells are considered unstable....
Bonding• Atoms with unfilled valence shells are
considered unstable.
• Atoms will try to fill their outer shells by bonding with other atoms.
• The number of valence electrons will determine how many bonds the atom can form.
• Two types of bonds we will discuss:– Ionic bonds– Covalent bonds 2
Ions Review• Ions are charged atoms (positive or negative).
• Ions are formed when atoms gain or lose electrons.
• Positive ions are called cations.– Formed when the atom loses electrons.
• Negative ions are call anions.– Formed when the atom gains electrons.
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Ionic Bonds
• Ionic bonds are formed between metals and non-metals.
• Ionic bonds are formed between oppositely charged atoms (ions).
• Ionic bonds are formed by the transfer of electrons.– One atom donates electrons to the other.
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Ionic Bonds (continued)• In an ionic bond one atom will lose its electron(s)
and the other will gain them.– Depends on the number of valence electrons.
• The transfer of electrons creates a positive ion and a negative ion.
• The opposite charges attract one another, causing a bond to form.
Bonding Animation 5
Drawing Ionic Bonds• We can illustrate ionic bonding using
Lewis structures.
• 1 – Draw the Lewis structure for each element.– Ex: Na Cl
• 2 – Draw arrows to show the gain/loss of electrons
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Drawing Ionic Bonds (continued)
• 3 – Draw ion Lewis diagrams showing the new charge for each ion.– Ex:
• The chemical formula for the compound formed represents the ratio of negative ions to positive ions.– Ex: NaCl – for every 1 sodium ion, there is
also 1 chlorine ion.
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Practice Drawing Ionic Bonds
Elements Lewis Ion Lewis Formula
Diagram Diagram
Calcium
Sulfur
Magnesium
Bromine
Aluminum
Oxygen8
Covalent Bonds
• Covalent bonds form between two non-metals.
• Covalent bonds are formed when atoms share electrons.– Both atoms need to gain electrons, so they
share the electrons they have.
• Atoms can share more than one pair of electrons to create double and triple bonds.
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Covalent Bonds (continued)• Atoms can share their electrons equally or unequally.
• When atoms share electrons equally it is called a non-polar bond.– Non-polar covalent bonds form between atoms of the same type. Ex:
H2
• When atoms share electrons unequally it is called a polar covalent bond.– One atom pulls the electrons closer to itself.– The atom that pulls the electrons more gets a slightly negative
charge.– The other atom gets a slightly positive charge.
• Ex: Water molecule
Bonding Animation 10
Drawing Covalent Bonds• We can illustrate covalent bonding using
Lewis structures.• 1 – Draw a Lewis structure for each element.
– Ex: C H
• 2 – Draw circles around the shared pair(s) of electrons.– Ex:
• 3 - Continue adding atoms until all atoms have a full valence shell.– Ex:
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