Naming Simple Compounds (2.8) Flashcards
What does IUPAC stand for?
International Union of pure and Applied Chemistry
How do you name binary ionic compounds?
Name the cation first and the anion second; the cation keeps its name and the suffix “ide” is added to the anion
Name the following:
Cesium fluoride
Aluminium chloride
Lithium hydride
What are the three steps of writing formulas for monovalent ionic compounds?
- Write the symbol for the metal first, and the nonmetal second
- Find their charges using the periodic table
- Criss-cross the charges; these charges become subscripts giving the compound an overall charge of 0
What is the zero sum rule?
The sum of the positive valances and negative valences must be 0
How do you name binary ionic compounds (multivalent)?
You show the charge using a roman numeral in brackets only if there is more than one possible charge on the cation
Name FeCl3 (multivalent)
Iron (III) chloride
According to the older alternative naming system, which endings were used for what?
“ic” was used for higher valence and “ous” for lower valence
What was the problem with the older alternative naming system?
Limited to elements with two valences
What is a polyatomic ionic compound?
An ionic compound that consists of ions of more than one element
What is an oxyanion?
A negatively charged polyatomic ion that contains oxygen
Describe the prefixes/suffixes for naming polyatomic compounds (chart)
What do the words “dihydrogen” and “hydrogen” mean when naming?
The number of hydrogen atoms that must be added
What does the prefix thio mean?
A sulfur atom has taken the place of an oxygen atom
What is a hydrate?
An ionic compound that has a water molecule/molecules trapped in its crystal structure
What is an anhydrate?
A hydrate written without water
How do you name hydrates?
Write the name of the compound; use a prefix to indicate the number of water molecules followed by the word hydrate
How do you name binary covalent compounds?
The first element is named using full element name; the second element has the suffix (“-ide”); use a prefix to show the numbers of atoms *mono is never used for naming the first element*
How do you know if a compound is an acid or a base?
The compound must be dissolved in water
How do you name bases?
Use the same rules as those for naming ionic compounds
How do you name binary acids (those that don’t contain oxygen)?
Add the prefix hydro and the suffix ic acid to the root name (e.g. hydrofluoric acid)
How do you name oxoacids (those that contain oxygen)?
For anions that end in ate, the suffix is ic acid
For anions that end in ite the suffix is ous acid
The prefix hypo and per remain the same in the acid’s name
What is a chemical bond?
A group of forces that holds atoms together
What is bond energy?
The energy required to break a bond
What is ionic bonding?
Occurs between metal and nonmetal
What is covalent bonding?
Occurs between two nonmetals in which electrons are shared
What is bond length?
The optimal distance between atoms that are bonded together where overall energy of a system is minimal
What is a polar covalent bond? (Provide example)
A covalent bond in which electrons are not equally shared by nuclei; a good example is HF (g)
What is a localized electron model (LE)
A molecule is composed of atoms that are bound together by sharing pairs of electrons using the atomic orbitals of bound atoms
Define lewis structure
Shows how valence electrons are arranged
What is the octet rule?
To be stable, most atoms within a compound want to achieve a noble gas electron configuration
What is the duet rule?
To be stable, hydrogen only requires 2 electrons
How do you write Lewis structures?
- Add up the valence electrons from all the atoms
- Write the central atom (the first one in the chemical formula) in the middle; place other atoms around it
- Join branch atoms to central atom using a pair of electrons; make sure all atoms get an octet
What are the rules pertaining to polyatomic ion lewis structures?
- Don’t forget to add electrons for negatively charged polyatomic ions
- To achieve an octet for the central atom a double bond might be formed
What are exceptions to the octet rule?
Boron has a diminished octet (only needs 6 electrons); sulphur can have an extended octet (uses the d orbital for this)
What are resonance structures?
When more than one lewis structure is possible
What is formal charge?
The difference between the number of valence electrons on the free atom and the number of valence electrons assigned to the atom in a molecule
How does formal charge work (explain the process)?
- lone pairs are said to belong to the atom they are on
- shared electrons are divided equally between two atoms
- to determine the number of valence electrons assigned for an atom in a molecule, we use:
What are the rules of formal charge?
- Calculate formal charge for each atom in a molecule
- Negative formal charges should reside on the most electronegative atoms
- The sum of the formal charges of all atoms in a molecule must equal the overall charge on that species
- The Lewis Structure with formal charges closest to zero is considered the preferred structure
What is VSEPR?
Valence shell electron pair repulsion; the structure of a 3D molecule, minimizing electron-pair repulsions
What are the steps for using VSEPR?
- Draw the lewis structure for a molecule
- Count the electron pairs and arrange them in a way that minimizes repulsion
- Determine the position of the atoms from the way the electrons pairs are shaped
- Determine the name of the shape from the positions of the atoms
What is a bond angle?
The angle formed between the nuclei of two atoms that surround the central atom of a molecule
What is the central atom?
The atom or atoms in a molecule that has the most bonding electrons
Where are bonding and non-bonding electrons found?
Bonding electrons are found between atoms while non-bonding (lone) pairs are found on atoms
What are the 3 types of repulsive forces? What’s the order of their repulsive forces?
Lone pair-lone pair
lone pair-bonding pair
Bonding pair-bonding pair
LP-LP > LP-BP > BP-BP
What is the difference between bond polarity and molecular polarity?
Bond polarity only determines if the bond is polar (look for the difference in electronegativity - if it is in the range of 0.5-1.7 then the bond is polar); molecular polarity determines if the whole molecule is polar
What is an intramolecular bond?
Chemical bond within a covalent molecule (polar and non-polar covalent)
What is intermolecular force?
Weaker interactions that occur between molecules
What is a crystalline solid?
A solid with a highly ordered arrangement of components (atoms, ions, molecules)
What is an amorphous solid?
A solid with considerable disorder in its structure
What is a lattice?
A 3D system of points showing the positions of the components making up the substance
What is a unit cell?
The smallest repeating unit of the lattice
What is used to study the structures of solids?
X-Ray diffraction
How does diffraction work?
When X-Rays are directed at a crystal, a diffraction pattern is obtained; the X-Rays reinforce or cancel each other based on how far they travel after they hit atoms; the distance between the atoms can therefore be calculated
What are atomic solids?
Solids that have atoms at the lattice points
What are ionic solids?
Solids that have ions at the lattice points
What are molecular solids?
Solids that have small molecules at the lattice points
What is closest packing?
Spherical atoms packed in layers surrounded by 6 other spheres
What is hexagonal closest packed (hcp) structure?
3rd layer atoms can lie directly over the 1st layer atoms (aba)
What is cubic closest packed (ccp) structure?
3rd layer atoms do not lie over 1st layer atoms (abc)
What happens to the 2nd layer in closest packing?
Atoms sit in the dimples created by the 1st layer
What is the sea of electron model?
Metal cations are surrounded by a sea of freely swimming valence electrons
Why are metals malleable and ductile?
Atoms can slide past each other
What is a Band or molecular orbital model?
Electrons travel around the metallic crystal in molecular orbits of the metal atoms
What do conduction bands explain?
Why metals are good conductors of heat and electricity
What are alloys?
Substances that contain a mixture of elements and have metallic properties
What is a substitutional alloy?
Host metal atoms are replaced by metal atoms of similar size
What is a interstitial alloy?
Smaller metal atoms occupy the interstices (holes) between host atoms
What is a netword solid?
Atomic solides with strong directional covalent bonds; a giant molecule
What is silica?
Silicon-oxygen compound SiO2
What are silicates?
They have O:Si ratios greater than 2:1 and contain anions; often contain metal cations to maintain neutrality
What does packing of the ions do?
It maximizes attractive forces and minimizes repulsive forces
Where are larger anions and smaller cations packed?
Larger anions are usually packed hcp or ccp; smaller cations are packed in the holes
What are the 3 types of holes in the closest packed structure? Order them by size
Trigonal, tetrahedral, octahedral
Octahedral > tetrahedral > trigonal
