Accelerated Chemistry U2: Ionic and Molecular Compounds

What are the two types of molecular compounds?

Acids and everything else.

What are the two ways electrons can exist in Lewis Dot Structure?

Either in bonds or in lone pairs.

What are diatomic?

A molecular compound between two atoms of the same element. Write the symbol with a two at the bottom. The diatomic are most of the halogens (F₂, Cl₂, Br₂, I₂) plus N₂ and O₂.

*What are acids?*

A molecular compound composed of a hydrogen and usually a polyatomic ion. Acids usually release a H⁺ in water.

permanganate

MnO₄⁻

What is the molecular compound trend for malleability?

Molecular compounds are brittle

What is the molecular compound trend for conductivity?

Molecular compounds do not conduct electricity

*What is the molecular compound trend for state of matter?*

Molecular compounds have varying states of matter at room temperature.

What is the composition of molecular compounds?

Non-metals + non-metals

What is the prefix for three?

tri

How do we draw atoms in 3d?

We denote them with their symbol.

What is the prefix for ten?

dec(a)

What is the prefix for two?

di

What are the polyatomic cations?

1) NH₄⁺ (ammonium)

hydroxide

OH⁻

*What is the ionic compound trend for state of matter?*

Solid at room temperature.

What is the prefix for eight?

oct(a)

What is the prefix for four?

tetr(a)

How is the name of ionic compounds determined?

(metal/cation) (non-metal/anion)~ide ex: sodium chloride

What is the ionic compound trend for color? CHECK THESE TRENDS WITH THE QUIZ TO MAKE SURE I DIDNT MISS NEW ONES

- Alkaline earth metals and alkali metals are white - Transition metals are a variety of colors/colorful - Iron ions are brownish (rust) - Copper ions are blue/green - Manganese is pink

What is the ionic compound trend for solubility?

- All the ones with sodium ions dissolve - All the ones with calcium ions does not dissolve - When the difference in charges between the cation and anion is greater, the bond is stronger. (2+ is stronger than +). When we dissolve things we break the bonds. Therefore a stronger bond is hard to break. So the lower the charge, the easier it is to break the bond and therefore dissolve it in water

What are the exceptions to the octet rule? -REMEMBER THIS AND APPLY IT APPROPRIATELY WHEN WE DRAW DOT STRUCTURES - IF YOU GET STUCK IT MAY BE AN EXCEPTION

- Hydrogen follows the duet rule, meaning it may be surrounded by two valence electrons instead of eight - B may be surrounded by 6 or 8 valence electrons - P may be surrounded by 10 or 8 valence electrons - S may be surrounded by 10, 12, or 8 valence electrons

How can we get more electrons in a dot structure? How can we get rid of electrons in a dot structure?

- We can take a lone pair from one atom and making it a sharing bond to get more electrons to another atom - We can get rid of electrons by getting rid of a bond and making it a lone pair

How can we determine if a molecule is polar?

1) Draw the 3d structure - not 3d because it doesn't show the correct direction 2) Draw the polar vectors onto the 3d structure's bonds 3) Add the vectors by breaking it into its components (x,y,z) 4) Draw the net polar vector Remember that shape matters so keep in mind that bonds may not be in the same plane If the individual polar bonds cancel, it's non-polar. If they add to something, it's polar.

What are the steps to find the 3D shape of a molecule?

1) Draw the dot structure of the molecule 2) Identify the central atom 3) Count the number of atoms surrounding the central atom, and add it to the number of lone pairs on the central atom. Call that number N. 4) Draw the shape around the central atom based on the number N. 5) Draw in the attached atoms and lone pairs on the central atoms. 6) Name the shape based on all *atoms* only - ignore lone pairs when naming the shape

What are the polyatomic anions?

1) NO₃⁻ (nitrate) 2) ClO₃⁻ (chlorate) 3) CH₃COO⁻ (acetate) or C₂H₃O² 4) OH⁻ (hydroxide) 5) SO₄²⁻ (sulfate) 6) CO₃²⁻ (carbonate) 7) PO₄³⁻ (phosphate The following are not in base polyatomic formula. ASK IF THIS IS TRUE 8) CN⁻ (cyanide) 9) O₂²⁻ (peroxide) 10) MnO₄⁻ (permanganate)

How do you draw 3d diagrams when there's more than one central atom?

1) Start with a random atom as the central atom 2) Move over the next central atom and draw it's diagram onto the other's diagram 3) For now, each central atom's atoms don't effect each other

What are the common acids?

1) hydrochloric acid/stomach acid (HCL) The following is acid rain: 2) nitric acid (HNO₃) 3) sulfuric aid (H₂SO₄) 4) carbonic acid (H₂CO₃) 5) phosphoric acid (H₃PO₄) - in soda! 6) acetic acid (HC₂H₃O₂ or CH₃COOH) - H is at the end for the second one and it's in vinegar!

*What is a molecular compound?*

A bond formed between two metals. Instead of transferring electrons and forming cation and anion parts that bond together, the two metals share electrons in order to reach eight valence electrons. Molecular compounds are not usually made up of ions -therefore they don't balance each other out. They share electrons across neutral atoms to reach a common goal.

What is a covalent bond?

A bond formed when electrons (valence electrons) are *shared.*

What is a non-polar bond?

A bond where electrons are shared evenly.

What is a polar bond?

A bond where electrons are shared unevenly.

What is a connectivity diagram?

A diagram simply showing which atoms are connected to what. It does not show the number of electrons or the number of bonds. Don't confuse this with dot diagrams - a single line doesn't mean there's one bond in this diagram!

How are acids named? How is the number of hydrogens determined?

Acids are named by polyatomic ion~ic/ric acid The exception is hydrochloric acid. The number of hydrogens in the acid is the number of H+ needed to balance out the other ion's charge.

What is the periodic trend for electronegativity of atoms?

Across: Bigger Down: Smaller Note: we do not talk about the noble gases because they are unlikely to form bonds Hydrogen exception ASK HOW HYDROGEN IS AN EXCEPTION

What is an ionic bond?

An ionic bond is an electrostatic attraction between oppositely charged ions (strong).

How do we draw lone pairs in 3d?

As a bubble shape with a line at the bottom. Remember to draw lone electrons only in pairs - they come together! They are stronger together 😏.

What is the trend for bond length vs. bond order in molecular bonds?

As more and more bonds are established between *two* atoms, bond length *goes down.*

What is the trend for bond energy vs. bond order in molecular bonds?

As more and more bonds are established between *two*atoms, bond energy *goes up* (gets stronger).

How does formal charges apply to Lewis Dot Structures?

Atoms need to have the proper amount of formal charges to match the charge of the molecular compound. Therefore, count 1 e- per bond to make sure the formal charge is appropriate. Draw the Lewis Dot Structure with bonds first then look at the octets first then the formal charges..

How does the octet rule apply to Lewis Dot Structures?

Atoms react tend to end up with/being surrounded by eight valence electrons. Therefore, our dot structure needs to follow the octet rule! The bonds, or shared electrons, helps the atom reach the octet rule. Therefore, count 2 e- per bond to make sure it is surrounded by 8 valence electrons (or another number if its an exception). When drawing dot structures, put the bonds somewhere so it the atom reached 8 valence electrons. *Bonds allow for the atom to gain electrons.* REMEMBER THE EXCEPTIONS!!!!

Which bonds are always polar? Which bonds are always non-polar? Which is more popular?

Diatomics and CH are always non-polar bonds. Basically everything else is polar! Polar bonds are more popular!

What are the two different ways an octet can be achieved in a Lewis Dot Structure?

By pairs or by lone pairs. Therefore, an atom doesn't need to reach electrons through bonds. We can add lone pairs and give it a charge!

*a*cetate

CH₃COO⁻ or C₂H₃O₂⁻

cyanide

CN⁻

*c*arbonate

CO₃²⁻

*c*hlorate

ClO₃⁻

What type of bond does a molecular compound have?

Covalent bond

How can we determine the angle between bonds of an atom?

First, we only look at the angle between the atoms, not the lone pairs. In the tetrahedral shape, without any lone pairs, the angle between two atoms is *109.5˚*. As we add lone pairs instead of atoms and *the atoms are still staying in different planes,* the angle diminishes by ~2. If they are all in the same plane, the angle depends on the shape.

What is the octet rule?

For ionic and molecular compounds, atoms react to end up with eight valence electrons.

What are the rules for deriving more polyatomic ions by changing the number of oxygens?

For ones that end in ~ate... 1. per...ate - one more O than ...ate and same charge 2. ...ate - the base polyatomic ion 3. ...ite - one less O than ...ite and same charge 4. hypo...ite - one less O than ...ite and same charge 1. perchlorate ClO₄⁻ 2. chlorate ClO₃⁻ 3. chlorite ClO₂⁻ 4. hypochlorite ClO⁻

What is electronegativity?

How much an atom attracts an electron in a bond. Atoms with high electronegativeity are like to form anions. The more electronegative an atom is, the more it attracts electrons.

Which acid is an exception?

Hydrochloric acid (HCL) because it is not contain a polyatomic ion.

Acids are usually made up of what and what?

Hydrogen and polyatomic ions

What are the three binary molecules with common names instead of the common binary naming?

H₂O > water (dihydrogen monoxide) NH₃ > ammonia CH₄ > methane (natural gas)

How are covalent bonds formed?

In molecular compounds, atoms react to end up with/being surrounded by eight valence electrons. In order to do this, they share electrons, forming a bond between the atoms.

What is the structure of molecular compounds?

Molecular compounds are comprised individual molecules - meaning they are not in one structure with many other molecular compounds. Each single compound is its own entity. However, ionic compound's structure is many cations and many anions bonded together.

What is the composite dot structure?

In resonance structures, we move around the double bond. Since the double bond is actually across the whole structure, the composite dot structure illustrates this. The composite dot structure is the average of all the resonance structures. We therefore get things like 1.33 bonds and -2/3 charges. It is a more accurate representation of what's going on. Composite dot structures distributes the charge evenly.

How do we find the charge of an atom in a composite structure? Lone pairs?

In the resonance structures, as the double bond mood around, so did the charge. Therefore, we average the charge in the resonance structure. For example, in the picture above, the upper O had a negative charge twice and no charge once. The average charge in the composite structure is -2/3 Lone pairs is still averaging, but please don't try to draw 2/3 lone pairs!!!! (remember that 2 lone pairs means 4 electrons).

What are the two kinds of compounds?

Ionic and molecular compounds.

What type of bond does an ionic compound have?

Ionic bond.

How are ionic bonds formed?

Ionic bonds are formed through a transfer of valence electrons between the metal and the non-metal. When they react, the metals looses valence electrons. The non-metal gains the metal's loosed valence electrons. Therefore they become ions. An electrostatic bond is formed between the positive and negative ions. Both ions have eight valence electrons.

What is the ionic compound trend for malleability?

Ionic compounds are brittle.

What is the ionic compound trend for conductivity?

Ionic compounds are electrolytes, which means they conduct electricity when dissolved in water. ex: an electrolyte in gatorade is salt because it is a dissolved ionic compound. Remember that these trends are for all ionic compounds - not just the polyatomic ions!! Don't confuse ionic compounds and polyatomic ions!

In a resonance structure, where is the double bond if it can be moved everywhere?

It's not in one place. *The double bond is spread over the whole structure because we can think of electrons as a fog.*

*What is a resonance structure?*

Lets says theres a nitrogen surrounded by three Os. There is one bond between the nitrogen and the oxygen except for one pair of atoms which has two. The problem is the the double bond should be shorter but its not. You could move the double bond but the dot structure is just equivalent. If we move the second bond around, we will get three equivalent dot structures. All three are resonance structures of each other. A resonance structure is the equivalent dot structure for some species.

What is the composition of ionic compounds?

Metals + non-metals.

How many of each ion is needed in order to make an ionic compound neutral?

Metals and non-metals loose a set amount of electrons. Since the non-metals takes in the metal's electrons, there must be enough non-metals to take in the number of electrons the metal looses and enough metals to supply the non-metal with enough electrons. Therefore, the charges must balance out. Look at the last unit quizlet to see how many electrons each group tends to loose/gain.

ammonium

NH₄⁺

*n*itrate

NO₃⁻

As the bond energies go up and the length goes down, is it by a factor of 2 or 3?

No

*In a covalent bond, are electrons shared evenly?*

No, because one atom is usually more electronegative than the other.

What are the different ways charge can be achieved in a Lewis Dot Structure?

One atom can be positive or negative and thats the end of the story *Or... multiple can be positive and multiple can be negative and the net charge matches what's given.* For example, two atoms could have a negative charge, and one could have a positive charge, so the net charge of the compound is 1-. *Remember.. in nature the less charges there are the better! So always go with the dot structure with less individual charges! - even if they are resonance structures of each other.*

How do we draw molecular compounds with a charge?

One of it has a formal charge that differs from its regular formal charge. 1) Draw the atom out with its bonds 2) See wether you have to add or take away electrons to meet the formal charge and the octet rule 3) Sometimes it works out so you don't have to add any 4) You can add/take away electrons either by just making up an electron or turning a bond into a lone pair or a lone pair into a bond

peroxide

O₂²⁻

*p*hosphate

PO₄³⁻

What are lone pairs?

Pair of e- (think in pairs!) that are not in a bond. So therefore 2 lone pairs means four electrons.

How are bonds thought about in molecular compounds?

We look at atoms group by group. We count how many bonds between the two atoms there is. As a whole, if there's two bonds, we say there's a double bond between the atoms.

What is a polar molecule?

Polar molecule is the net of all the polar and non-polar bonds of a molecule. It describes whether the whole molecule, not the individual bonds, is polar or non polar based on the individual bonds.

*s*ulfate

SO₄²⁻

What is the bent shape of a molecule? When does it occur?

Shape: 2 electrons in the plane of the paper (2d) that is not completely flat like linear Number of atoms (discarding central atom): 2 Angle: depends Formed: when there are not enough atoms to make a 3d shape but there are still lone pairs so the atoms are not in a direct line to each other

What is the tetrahedral shape of a molecule? When does it occur?

Shape: Cheerleader figure Number of atoms (discarding central atom): 4 Angle: 109.5˚ Formed: only when there are 4 atoms and 0 lone pairs.

What is the pyramidal/trigonal pyramid shape of a molecule? When does it occur?

Shape: a pyramid Number of atoms (discarding central atom): 3 Angle: 107.5˚ Formed: only when there are 3 atoms and 1 lone pairs.

What is the trigonal planar shape of a molecule? When does it occur?

Shape: a triangle shape Number of atoms (discarding central atom): 3 Angle: 120˚ Formed: only when there are 3 atoms and 0 lone pairs

What is the linear shape of a molecule? When does it occur?

Shape: flat in a line Number of electrons (discarding central atom): 1 or 2 Angle: no angle when there's only 1, angle of 180˚ when there are 2 (three atoms in a line) Formed: When there's only 1 atom surrounding it or when there's 2 atoms and 0 lone pairs

Which transition metals, are exceptions or have a set charge?

Silver ion is always Ag⁺ Zinc ion is always Zn²⁺

*What are Lewis Dot Structures?*

Simple structures representing molecular compounds. It shows the valence electrons as dots and the bonds in the compound (the shared electrons) as lines between the atoms.

*What is a polyatomic ion?*

Some ionic compounds are made up of more than just 2 ions. A polyatomic ion is a group of atoms with a charge. They pair with another ion of the opposite charge to make a ionic compound. They end in ~ate for the most part.

What are the different shapes of molecules?

Tetrahedral, pyramidal/trigonal pyramid, trigonal planar, bent, linear.

What are valence electrons?

The number of electrons in the highest energy level of an atom?

What are formal charges?

The number of valence electrons that an atom owns - therefore not borrowed from another atom. If is neutral, the formal charge is just the number of valence electrons it usually owns. If it is positive, it has one less electron, and if it is negative, it has one more electron.

What is the structure of ionic compounds?

They are all together in one structure, with alternating atoms (elements).

How should electrons be drawn in Lewis Dot Structures?

Think in pairs!

What is the maximum number of bonds in a molecular compound?

Three

How do we find the name/formula of ionic compounds with transition metals?

Transition metals loose varying electrons. Therefore, we don't know the number of valence electrons losses. Therefore, in the name there *must* be a roman numeral that indicates how many electrons it looses. We find the name from the formula by seeing what charge is needed to balance it out. Ex: iron (III) chloride The charge of iron is 3+.

How are polar bonds shown in symbols?

Two ways 1) δ− or δ+ Mean's it's partially negative or positive 2) Polar vectors - an arrow pointing to where electrons are attracted to with a dash at the end

How can we find the chemical formula for ionic compounds?

Two ways: 1) The visual representation of electrons transferred. We draw a dot structure and see how many of each is needed to compensate for how many electron on atom looses/gains. 2) We can also list the charge of each ion. We need to see how many of each atom is needed in order for the charge of one atom to equal the charge of the other. This will make the charges balance out and the atom neutral.

*How are binary (two elements) molecular compounds named?*

Using prefixes to denote how many atoms of the element is in the compound. The only time you don't use prefixes is if the *first element has only one.* Furthermore, you still add the ~ide to the second element. ex: carbon monoxide dichloride pentoxide Still put mono if the second one is one! Note: finding the chemical formula is easy! Just put the symbols down in the order and write how many of each element there is by the prefix! When the prefix ends in a vowel (mono, hexa, etc.) take out the vowel when the elements name starts in a vowel (monoxide). CHECK IF THE FOLLOWING SECTION IS TRUE!!!

*What is VSEPR theory?*

Valence shell e-pair repulsion - the idea that all atoms and lone pairs will get as far away from each other as possible in 3-d.

How do we find the amount of bonds between two atoms in a composite structure?

We average how many bonds were in the resonance structures. For example, in the picture above the left C and O have 1 bond, then 2 bonds, then 1 bond. We average this out get that in the composite structure, this is 1.33 bonds between these two. We can calculate the energy and length of the bond by doing 1.33 multiplied by the energy/length for bond 1.

*What is an ionic compound?*

When a metal and a non-metal react, they tend to loose or gain elections, causing them to form ions. An ionic compound is the result of a transfer of elections between metals and non-metals as the metal looses the elections and the non-metals gains the electrons. Therefore, ionic compounds are made up of two ions, joined by an electrostatic charge, that balance each other's charges out to make one neutral compound.

What two rules should we keep in mind when drawing Lewis Dot Structures?

When drawing Lewis dot structures, always check the: 1) Octet Rule 2) Formal Charges

How are polyatomic ions written/seen in chemical formulas?

When there are multiple of one polyatomic ions, they are placed in parentheses. Al₂(CO₃)₃ A chemist sees this chemical formula as two parts - the cation and the anion- not three parts even though there are three atoms.

How can we determine the shape of a molecule?

Whene determining the shape, *we only look at the shape of the atoms,* not the lone pairs!

How do we draw the composite dot structure?

With dotted lines representing the double bond that's spread across the atom.

What are the rules of deriving more polyatomic ions by changing the adding hydrogens and adjusting charge?

You vary the charge by adding a hydrogen 1. bi- means add one positive hydrogen (H⁺) to make the charge one more positive 2. di- means add two positive hydrogens (2H⁺) to make the charge two more positive Note: the name can be bicarbonate or hydrogen carbonate, it's also called dihydrogen phosphate

What is the prefix for seven?

hept(a)

What is the prefix for six?

hex(a)

What is the prefix for one?

mon(o)

What is the prefix for nine?

non(a)

What is the prefix for five?

pent(a)