Bell Work 3-Nov-2016 How many valence electrons do magnesium and oxygen have? Yesterday we talked about certain atoms losing e- when they combine with others and other atoms gaining e- when they combine. How do you think Mg and O will combine?

QUIZ 1.4 Write the LONG-HAND WRITTEN electron configuration for P. Write the SHORT-HAND ORBITAL DIAGRAM for P.

ANSWERS 1s2 2s2 2p6 3s2 3p3 2pts [Ne] 3s ↑ ↓ 3p ↑ ↑ ↑ 1pt

Objective: You will UNDERSTAND how to determine an element from a compound from their chemical formulas. You will also understand how ionic bonds form to create ionic compounds.

Element or Compound? Recall back to our discussion of matter and its classification. What are the two types of “pure substances”?

Elements: composed of only one type of atom Elements: composed of only one type of atom. All atoms of the same element have the same number of protons. Ex: Al, P, Sodium Compounds: substances composed of a definite proportion of two or more elements. Ex: Sugar (C6H12O6), Table salt (NaCl)

Of the following, which are elements and which are compounds? B ZnBr2 F CO2 Sr NH4Cl

Chemical Formulas The compounds we just looked at are written as chemical formulas. A chemical formula gives the number of atoms of each element in a compound. Contains the elemental symbols for the elements in the compound, and the number of each atom in the form of subscripts. EX: CO2

Compounds In our study of compounds, we will be looking at two types: Ionic Compounds Covalent Compounds

Ions Some compounds are composed of particles called “ions” An ion is an atom (or group of atoms) that has a positive or negative charge Atoms are neutral because the number of protons equals electrons Positive and negative ions are formed when electrons are transferred (lost or gained) between atoms

Ionic Compounds Ionic compounds contain ionic bonds Formed when e- are given/ taken between two atoms. e- are exchanged between atoms so that each atom will have a full outer shell (octet rule).

Ionic Compounds When e- are given/ taken, ions are formed, & the + ions attract the - ions. Positive ion = Cation (Usually a metal, no change in name) Negative ion= Anion (Usually a nonmetal, usually ends in ide, ate, or ite)

Example of how ionic bonds are formed… Li 3 p+ F 9 p+ e- e- e- e- Wants to get rid of 1 e- Wants to gain 1 e-

… since there is a mutual need to give and take one e-… Li 3 p+ e- F 9 p+ Gives the 1 e- to F, to achieve a full outer level and… F gladly takes the 1 e- from Li to also achieve a full outer level.

Li and F have now become IONS! 9 p+ e- Li+ 3 p+ Li has 3 p+ and 2 e- F has 9 p+ and 10 e- Now, Li has a charge of Now, F has a charge of +1 -1

Remember the rules of attraction! Since lithium is +1 and fluorine is –1, they are attracted to each other since… OPPOSITES ATTRACT! Now, together, they make… F -1 Li +1 or… LiF

Closure Cliff Notes: Write a short cheat sheet that would be helpful for a quiz on today’s learning.

1. What is the frequency of a 2.00 x10^(-12) m wave? 2. What is the energy of this wave? If the difference between the n=1 and n=2 energy levels of an atom was 8.1x10^(- 14) J, could the atom absorb this photon?

Bell Work 11-4-16 Correctly write the ion, showing oxidation number. Formula Cation or Anion Nitride Chloride Sodium Oxide Calcium Phosphide

and Research/ Problem Idea due 7.Nov.2016 Objective: Be able to name ionic compounds and correctly write their chemical formulas. Science fair: Partners, Notebook, and Research/ Problem Idea due 7.Nov.2016

Diatomic Elements Back to elements really quick: Some elements exist in nature as what we call “diatomic” Means two atoms of the same element. 7 Elements behave this way: H2, N2, O2, F2, Cl2, Br2, I2

Back to Ionic Compounds Polyatomic Ions: Groups of atoms (covalently bonded together) that have a (+) or (-) charge Take out Periodic Table On the back, there is a list of polyatomic ions Try to become familiar with these.

Polyatomic Ions When do we use ate/ite? Sulfate = SO42- Sulfite = SO32- Nitrate = NO3- Nitrite = NO2- What is the difference here?

Writing Ionic Formulas To write the chemical formula for ionic compounds, we must balance the charge between the ions Our compounds are neutral, so we must add as many of our + and – ions to make the total charge 0.

An easy way to do this, it to write out the ions of the compound first. Ex: Sodium Chloride Na+ Cl- Then, we “criss-cross” the charges by making the charge of the opposite ion the subscript of the formula. NaCl

Another Example: Barium Fluoride Ba2+ F- BaF2 Another example: Aluminum Oxide Al3+ O2- Al2O3

HOLD UP This doesn’t work all the time. Ex: Barium Oxide Ba2+ O2- Ba2O2?!??!?! No. BaO

Ion Chip Practice Use the ion “chips” to make each of the compound on the list. Then write the correct chemical formula. Do not loose the ions chips and return to the bag when finished. Ex.

Bell Work 11-7-16 Using your knowledge of ions, write the chemical formulas of the following ionic compounds. (use your periodic table, front and back) Sodium chloride Barium sulfate Lithium phosphate Aluminum oxide Beryllium phosphate

Ionic Compounds Ionic Compounds with Transition Metals. We’ve kind of ignored these until now, but now we’ll take a look at what these do.

Oxidation States Transition metals have more than one oxidation state Oxidation State: a number assigned to an element that represents the # of e- lost or gained. The elements we’ve been looking at until now only have 1 oxidation state Group 1’s oxidation state is +1 Group 7’s oxidation state is -1

Oxidation States

Practice FeCl2 CuO CoBr2 Ni(NO3)2 Determine the oxidation state of the transition metal in the following ionic compounds FeCl2 CuO CoBr2 Ni(NO3)2

Official Rules for naming Ionic Compounds To name an ionic compound, you must follow the following rules: ALWAYS name the CATion before the ANion. Never name NaCl “Chloride Sodium” When naming a transition metal CATion, you must include the oxidation state in () with Roman Numerals FeCl2 would be “Iron (II) Chloride” The names of polyatomic ions do not change. NH4Cl is “Ammonium Chloride” (NH4)2SO4 is “Ammonium Sulfate”

Practice KCl FeO NiCl2 Rb2S Al2(SO4)3 Name the following Ionic Compounds: KCl FeO NiCl2 Rb2S Al2(SO4)3

Covalent Compounds Now, we will start to look at covalent (molecular) compounds. Molecular compounds contain “covalent” bonds between NONMETAL atoms. VAST # of different covalent compounds.

Covalent Compounds Covalent Bonds: These occur when electrons from one atom feel a pull from the nucleus of a neighboring atom. The atoms then share one or more electrons to fill each others valence shells. The degree of sharing between the atoms is dependent on the difference in electronegativity between the atoms.

Covalent Bonds The degree of sharing between the atoms is dependent on the difference in electronegativity between the atoms. e- are in constant motion, so in a covalent bond, they will be moving around each of the atoms. e- will spend more time around more electronegative atoms. This leads to interesting properties (which we will discuss later)

Naming Binary Covalent Compounds Since we can predict the chemical formula of ionic compounds just based on the ions present, we don’t need to include the # of each ion when naming them. With covalent compounds, this is not the case. We need a way to indicate the # of atoms for each element in the compound.

Naming Binary Covalent Compounds In order to indicate the # of each element, we use prefixes in front of each element. Unless there is only 1 atom of the first element in the compound. EX: CO2 is named “Carbon dioxide” EX: H2S is named “Dihydrogen monosulfide”

Numerical Prefixes List of prefixes for numbers: 1 = mono- 2 = di- 3 = tri- 4 = tetra- 5 = penta- 6 = hexa- 7 = hepta- 8 = octa- 9 = nona- 10 = deca-

Practice Name the following binary molecular compounds: H2O NO NO2 CO2 S2F10