FINAL EXAM- Compounds and writing formulas Flashcards
Ionic compound
A compound formed between a cation (positively charged ion) and an anion (negatively charged ion). Ex. Metal and nonmetal
Covalent compound
A compound formed between two nonmetals.
Subscript
little number below every element that indicates the number of atoms/ions of the element it follows.
Polyatomic ions
an ion made of two or more atoms (that list she gives us on the back of the periodic table. Ex. SO4/sulfate)
cation
An ion that has a positive charge.
Conductivity
The degree to which a specific material conducts electricity.
Anion
An ion that has a negative charge.
Formula unit
The smallest part/particle of an ionic compound.
Molecule
smallest part/particle of a covalent compound.
Binary
compound with 2 elements
Tertiary
compound with more than 2 elements.
Acid
Proton donors. Compound that starts with H.
Base
Proton acceptors. Compound that ends with OH
Salt
all ionic compounds except acids and bases.
Oxidation numbers
The number of electrons that must be added to or removed from an atom in a combined state to convert the atom into the elemental form. (Ex. Na’s oxidation number is +1, S’s is -2)
Lewis dot diagram
a structural formula in which electrons are represented by dots; dot pairs or dashes between two atomic symbols represent pairs in covalent bonds.
How to name a binary compound
- All binary compounds end in –ide
- Name the metal first
- Then name the nonmetal and change the ending to –ide
- Ex. KBr= Potassium Bromide
- Subscripts do not affect the naming
- AlI3= Aluminum Iodide
Know how to name a tertiary Ionic compound
- Don’t end in –ide
- All contain polyatomic ions
- Name metal, then name polyatomic ion
- Ex. CaSO4= Calcium sulfate
- KNO3=Potassium Nitrate
- Subscript still doesn’t matter
- All compounds that end in –ide are not all binary (since there are polyatomic ions that end in –ide), but all Binary compounds end in –Ide
Know when to use oxidation numbers when writing a formula
- Use oxidation numbers to ensure that the net charge of your formula is zero
- Add subscripts as necessary based off the oxidation numbers to make the net charge zero
- Ex. Ca’s oxidation number is +2 and Br is -1, so to make the net charge zero for the binary compound, you would make Br have a subscript of 2 so it ends up being CaBr2
- It’s the same for tertiary compounds
- Ex. Cs’s oxidation number is +1 and PO4’s is -3 so it would end up being Cs3PO4
Know when to use Roman numerals when naming a compound
- Roman numerals indicate the charge of metal ion
- Use with transitional metals
- Ex. Tin (IV) oxide= Sn+4O-2=SnO2
- If you were given CrBr3, you know that Br has a oxidation number/charge of -1 and you know that there are 3 of them, so the charge of Br has to be +3 to cancel it out and make the net charge zero. So it would be Chromium (III) Bromide
Know when to use Greek Prefixes when naming compounds and prefixes
- Use with covalent bonds
- Ex. N2O5= Dinitrogen Pentaoxide
- Prefixes
- Mono
- Di
- Tri
- Tetra
- Penta
- Hexa
- Hepta
- Octa
- Nona
How to draw a Lewis dot diagram for Ionic bonds
- Determine which element has less electrons
- Represent the element that gives the electron with the blank element, with no electrons around it, in brackets, and a charge of +(however many elements it gave)
- Represent the elements that took the electrons in brackets with 8 electrons around it and a charge of –(however many it took)
- Might have to have more than one giving element to fulfill 8 electrons (like Li2O)
- Below are the Lewis dot diagrams for NaCl and Li2O
- No line structures for Ionic bonds
How to draw a lewis dot diagram and line structure for covalent bonds with ions
- Start by drawing the lewis dot diagrams and line structure the way you normally would (consult CCl4 and BeAt2 examples above)
- The only difference is that with polyatomic ions, you have to include brackets and charges
Know how to determine if an unknown is ionic or covalently bonded in a lab.
- Ionic compounds (as a solution or liquid/melted) can conduct electricity
- Covalent bonds do not conduct electricity (because they have no free electrons and no ions)
- So in a lab, if it can conduct electricity it is Ionic and if it can not, it is covalent.
- Ionic compounds tend to be soluble in water
- Ionic compounds have a high melting point
What type of ion is always found written first in a chemical formula?
cation
