CHEMICAL BONDINGObjectives: Can you identify ionic and covalent bonds?Can you name chemical compounds?

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PROPERTIES OF IONIC COMPOUNDS They are crystalline solids at room temperature (like salt) They have high melting points They conduct electricity when they are dissolved in water or when they are in molten stat e(heated up so high they turn into liquid)

They are made up of metals and nonmetals

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IONIC COMPOUNDSWhat holds ionic compounds together?

The difference in charges between the ions. Opposites attract.

How are ions formed? When electrons are transferred from one element to another. The atom becomes an ion because the number of protons and electrons are no longer equal creating charges.

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CONDUCTIVITY Ionic compounds are non-conductors but they are conductors when in aqueous solution. What does that mean?

When ionic solids are melted or dissolved, they break into ions.

The electrically charged ions are then free to move. Their motion conducts electricity Strong vs Weak Electrolytes

What are electrolytes?Conductivity videos

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IONIC BONDING If an element gains electrons, the charge is negative If an element loses electrons, the charge is positive.

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REVIEW PERIODIC TABLE Each group has a specific charge.

Groups are columns. Look at your periodic table and label the charges associated with the group.

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IONIC BONDS Involves electrostatic attraction between opposite charges of atoms.

Cations Positively charged atoms.

Anions Negatively charged atoms. Ends in -ide

Cations and Anions come together to form ionic compounds

Examples: Sodium + Chlorine Sodium Chloride Na+ + Cl- NaCl

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IONIC BONDS CONTINUEDWhat if the charges are different?

Example: Lithium (1+) and Oxygen(2-) Criss-cross the numbers and bring them down.

Why? Because the charges are different in ratio 1:2, criss-crossing will cancel the

charges out to make a stable compound. Transition elements with different charges have their charges in parenthesis like Iron (II) Fe2+ and Iron (III) Fe3+ , or Copper (II) Cu2+ and Copper (III) Cu3+

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MOLECULAR/COVALENT BONDING Instead of using charges to bond, covalent bonds share electrons.

Also called a molecular compound. They can have unequal amount of electrons

This causes polarity One side has more electronegativity

Polarity Depends on shape of the molecule and orientation of bonds Nonpolar substances have an equal amount of sharing and there is no

pulling Electronegativity – The tendency of an atom to attract electrons toward itself

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CHARACTERISTICS OF COVALENT COMPOUNDSGases, liquids, and brittle solids (like Carbon) at room temperature

Low melting pointsDo not conduct electricity when dissolved in waterMade up of nonmetalsCovalent compounds video

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PROPERTIES OF MOLECULAR COMPOUNDSAppearance of pure molecular compoundsMost molecular compounds are liquids or gases at room temperature

Some are solids and have crystalline structure and are brittle.

Some are solids and have a powder-like appearance and are soft.

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CHEMICAL BONDSWhy do atoms bond? (phet stimulation)

Stability Interactions/attractions

Chemical bond – electrical attractions that hold atoms together and lower the energy state of the system (they become more stable)

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COVALENT BONDING NOMENCLATURE If a compound has two or more nonmetals, they are written with prefixes of the number of that atom.

Example: CO2 Carbon Dioxide N2H4 Dinitrogen Tetrahydride

1 – Mono (for the second element) 6 - Hexa 2 – Di 7 - Hepta 3 – Tri 8 – Octa 4 – Tetra 9 - Nona 5 – Penta 10 – Deca

If the next word after the prefix starts with the vowel the “a” in the prefix is dropped. Example: Hexafluoride vs. Hexoxide, not Hexaoxide.

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POLYATOMIC IONSGroups of atoms that are covalently bonded together and have a charge on the whole group.

They function like any other single atom ion and combine with any charged ion.

Examples: Sulfate SO4

2-

Carbonate CO32-

Nitrate NO3-

Ammonium NH4+

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POLYATOMIC IONS CONTINUED Most polyatomic ions have different amount of hydrogens oxygens and they are named according to how much more or how much less hydrogen or oxygen the polyatomic ion has.

Chlorate vs. Chlorite vs. Perchlorate vs. Hypochlorite (there will never be a hypochlorate or perchlorite) -ate = the median amount of oxygen atoms -ite = one less oxygen than –ate Hypo= one less oygen than –te Per = one more oxygen than -ate Hypo-, -Ite, -Ate, Per-

Sufate vs. Sulfate. Nitrate vs. Nitrite

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POLYATOMIC ION PRACTICE1. ClO1-  

2. SO42-  

3. NO31-  

4. CO32-  

5. PO33-  

6. Ammonium  

7. Perchlorate  

8. Acetate  

9. Permanganate  

10. Hydroxide  

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ACIDS NOMENCLATURE Elements that are combined with Hydrogen become binary acids.

HCl, HBr, HF Nomenclature: Hydro+(element)-ic + acid.

Hydrochloric acid Hydrofluoric acid What is Bromine + Hydrogen?

Polyatomic ions that combine with Hydrogen become ternary acids HSO4, HClO3 Nomenclature: Ends with –ous or –ic + acid

-ate-ic, -ite-ous Sulfate SO4

2- with Hydrogen H2SO4 (Sulfuric acid) Nitrite NO3

- with H+ HNO3 (Nitrous acid) What is Nitrate + Hydrogen?

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ACIDS NOMENCLATURE PRACTICE

1. HI

2. H3P

3. HClO3

4. H2SO4

5. Sulfurous Acid

6. Chromic Acid

7. Chlorous Acid

8. Oxalic Acid