Agenda 12/9/19 Period 7

Quick check - review questions

Notes - Covalent bonding - any big questions?

Naming Covalent compounds (that are not organic) Pogil

- Complete and turn in

Chemical Reactions lab - preparation for tomorrow. Quick Check - review. 1. When drawing electron dot diagrams a. What do the dots represent? b. What does the element symbol represent? 2. Write the correct electron dot diagram for a. A carbon atom. b. An oxygen atom c. A hydrogen atom Quick Check - review. 1. When drawing electron dot diagrams a. what do the dots represent? Valence electrons b. What does the element symbol represent? 2. Write the correct electron dot diagram for a. A carbon atom. b. An oxygen atom c. A hydrogen atom Quick Check 3 - review. 1. The symbol in an electron dot diagram represents the atom’s nucleus and its inner electrons. 2. Write the correct electron dot diagram for a. A carbon atom. b. An oxygen atom c. A hydrogen atom (on whiteboard) For two elements with roughly the same electronegativity values, the valence electrons are going to be shared through a covalent bond

COVALENT BONDING http://academic.brooklyn.cuny.edu/biology/bio4fv/page/covalent_bonds.html

Here are 2 hydrogen atoms, showing the proton in the nucleus and the single electron in the first energy level.

p p

But neither of these hydrogen atoms are stable – they don’t have a full outer energy level. They react to get a full outer energy level.

This is a molecule of an element since it is only made up of hydrogen By overlapping the energy level the electrons can move atoms. around both hydrogen nuclei and hold them together We can make in a molecule (a diatomic molecule, because there hydrogen are 2 atoms). molecules by reacting acid with Mg Hydrogen atoms are not found in nature, but hydrogen molecules (H2) can be.

Lewis dot diagram H : H

Here are 2 chlorine atoms, showing the 17 electrons and the nucleus as a green sphere with the 7 electrons in the outer energy level.

But neither of these chlorine atoms are stable – they don’t have a full outer energy level. They will react to get a full outer energy level.

This is a molecule of an element since it is only made up of By overlapping the outer energy level the electrons can chlorine move around both chlorine nuclei and hold them atoms. We saw green together in a molecule (a diatomic molecule, chlorine gas because there are 2 atoms). react with sodium to make salt in a Chlorine atoms are not found in nature, but chlorine video clip molecules (Cl2) can be.

Lewis dot diagram

Other elements that exist as diatomic molecules because of covalent bonds (sharing electrons). Molecular formula Name

F2 (g) fluorine gas

N2 (g) nitrogen gas O oxygen gas 2 (g) Br bromine liquid 2 (l) I iodine solid 2 (s)

NOTICE – these are all nonmetal elements. Make models

But neither of these chlorine atoms are stable – they don’t have a full outer energy level. They will react to get a full outer energy level. Properties of Covalently Bonded Materials STP All gases at STP Standard • Elements temperature – Hydrogen H2 (diatomic) and pressure gas 0.00°C and 1 – Oxygen O (diatomic) gas atmosphere 2 – Nitrogen N (diatomic) gas pressure 2 – Fluorine F2 (diatomic) gas

– Chlorine Cl2 (diatomic) gas http://resources.schoo Kinetic lscience.co.uk/BAMA/ 14-16/aerosch2pg1.ht energy 2 ml = ½ mv kinetic = movement • The covalent bond between the atoms is strong, holding the atoms together in a molecule • But the forces in between individual molecules are weak – Weak intermolecular forces (older texts refer to van der waals forces) – the molecules are not attracted to each other, stay far apart in the gas phase Boiling point is the • These elements have extremely temperature at low boiling points which the vapor pressure – We know them all as gases, which of a liquid means the liquid phase only exists equals the external below STP (0°C and 1 atmosphere) atmospheric pressure, at this temperature all molecules in a liquid have enough energy to vaporize What about Bromine (Br2) – a liquid at STP Bromine (Br2) and iodine (I2)? Boiling point is 59.35° C Notice some of With this much the molecules Molecular mass of Br2 mass the have enough 2 x av. At.mass molecules just energy to don’t have enough escape into 79.9 +79.9 = 159.8 amu energy to all be vapor phase vapor at STP or below the even room boiling point of temperature; the liquid intermolecular Intermolecular – forces become like an interview – significant here between two people Iodine(I2) – a solid at STP What about MELTING point is 113.6° C Bromine (Br2) and iodine Molecular mass of I2 (I )? 2 2 x av. At.mass

126.9 +126.9 = 253.8 amu **Notice the molecules are still present This is the in the crystal lattice crystal lattice for iodine high mass of the iodine molecules – not moving as quickly as lower mass molecules

intermolecular forces are sufficient to hold the molecules close together in an organized way – a crystal lattice

http://www.webelements.com/iodine/crystal_structure.html Carbon - Allotropes Diamond One of hardest known materials – used to cut granite, concrete, glass Colorless Shiny Does not conduct electricity

Each carbon atom shares an electron with 4 other carbon atoms to form 4 covalent bonds - in a tetrahedral arrangement in space

Macromolecular solid Giant covalent structure Carbon - Allotropes One of softest known materials – graphite slippery (used as a lubricant) grey Shiny Does conduct electricity

Each carbon atom shares an electron with 3 other carbon atoms to form 3 covalent bonds - in a flat layer. The fourth electron from each atom gets “delocalized” between the layers, hold layers together loosely

Macromolecular solid – giant covalent structure For two atoms with a small difference in electronegativity values, the valence electrons are likely to be shared, but unequally through the covalent bond - polar molecules nonmetals Molecules of compounds: have tightly held Different nonmetal elements can be valence bonded together by overlapping electrons their outer energy levels so the

Share valence electrons can move electrons to get full around atoms of different outer energy level elements and hold them together in a molecule of a compound. Hydrogen Oxygen reaction Summary of Covalent Bonding So far: • Atoms (usually nonmetals) share valence electrons (cooperate, coexist, cohabit) • Sharing electrons forms a covalent bond between the atoms • Covalent bonds between atoms form molecules (usually gases, can be liquids, even solids sometimes) • Can have molecules of elements (same atoms) • Diatomic molecules have 2 atoms in them • Can have molecules of compounds (different atoms) • Covalent bonds can be single, double or even triple Shapes of molecules

1) HCl hydrogen chloride

2) CO2 carbon dioxide

3) CH4 methane

4) H2O water

5) NH3 ammonia

6) CH3Cl chloromethane Naming Molecular Compounds (that are not organic)

Notice:Non-metals bonded to non-metals By covalent bonds - completed Packet up to and including 14. Should be be ready to:

12. Share your idea how a prefix is modified when being used to name some molecular compounds. 12.

If a prefix ends in vowel and the element begins with a vowel, the vowel on the prefix is removed. Vowels are generally not repeated. 13. What about NI3?

Nitrogen tri-iodide is easy to say even though there is a repeated vowel.

If a prefix ends in vowel (a or o) and the element begins with a vowel (o), then the vowel on the prefix is removed. 14.

All of the compounds listed in Model 2 are binary molecular compounds. Compounds such as CH3OH or PF2Cl3 are not binary, and compounds such as NaCl or CaCl2 are not molecular. Propose a definition for “binary molecular compounds.” 14.

Binary molecular compounds contain 2 non-metallic elements only. 15. Rules for recognizing and naming binary molecular compounds from their chemical formulas: 1) Binary molecular compounds can be recognized because they contain 2 nonmetal elements only ( or a metalloid with a nonmetal). 2) Write a prefix in front of the name of the first element that corresponds with the subscript for that element, unless there is only one atom of the first element. In that case just write the name of the first element. 15. Rules cont. 3) Write the prefix corresponding to the subscript for the second element in front of the name of that element. 4) If a prefix ends in either an “a” or an “o” and the name of the element begins with an “o”, drop the final vowel from the prefix. 5) Remove the ending from the name of the second element and replace it with the suffix -ide. 16. Do these rules apply in these examples? Explain.

FeI3 ICl5 HBrO4 16. Do these rules apply in these examples? Explain.

FeI3 ICl5 HBrO4

Fe is a metal Yes, rules Not binary, Not a molecular apply rules do not Compound apply Rules don’t apply 17. Use the rules to name the molecular compounds. Molecular formula Molecule name

PBr3

SCl4

N2F2

SO3