CH. 3 Flashcards
metal atom
becomes a cation (a positively charged ion)
nonmetal atom
becomes an anion (a negatively charged ion )
formation of ionic compound
a metal loses an electron (Na+), a nonmetal gains electron, (Cl-)
- oppositely charged ions are held together by ionic bonds,
covalent bond // ( molecular compounds)
- when nonmetal bonds with another nonmetal, electrons are not transfered but rather shared
- there are NO ions!! No charges!!
- electrically neutral
- gives accurate representation of the compound
Chemical formulas
empirical (relative): CH
molecular (actual): C2H2
Diatomic molecules (molecular elements)
H2(hydrogen), N2 Nitrogen), O2 (oxygen), F2 (fluoride), Cl2 (chlorine), Br2 (bromine), I2 (iodine)
polyatomic ions
ion composed of two or more atoms
- a compound composed of a metal and a polyatomic ion; therefore, is an ionic compound
atomic element
- single atoms as their basic unit
Ex: Xenon
Difference between ionic and molecular compounds
- Molecular compounds contain highly directional covalent bonds, which result in the formation of molecules.
- Ionic compounds contain nondirectional ionic bonds, which result (in the solid state) in the formation of ionic lattices
Naming molecular compounds (two or more nonmetals)
(prefix)(name of first element)(prefix)(base name of 2nd element + -ide)
Prefixes for molecular compounds (two or more nonmetals!!)
- mono = 1 (ommitted for the first element in the formula)
- di = 2
- tri = 3
- tetra = 4
- penta = 5
- hexa = 6
- hepta = 7
- octa = 8
- nona = 9
- deca = 10
acids
- molecular compounds that release hydrogen ions when dissolved in water
- usually written first in their formula, and one or more nonmetals, written second
- sour taste
- ability to dissolve many metals
- 2 types: binary acids and oxyacids
- formula has H as first element
aqeous
- dissolved in water
- Ex: HCl (aq): hydrochloric acid (an acid when dissolved in water)
- differs from HCl (g) - hydrogen monochloride
Naming Binary Acids
- Hydrogen and a nonmetal
- (hydro)(base name of nonmetal + -ic)(acid)
ex: HCl (aq): hydrochloric acid
HBr (aq): hydrobromic acid
HI (aq): hydroiodic acid
Naming OxyACIDS
- contain hydrogen and an oxyanion (an anion containing a nonmetal and oxygen)
How do chemical bonds form?
- chemical bonds form because of the attractions between charged particles (the electrons and protons) that compose atoms
- like charges repel, opposite charges attract
empirical formula vs. molecular formula
- empirical: gives the relative number of atoms of each element in a compound – communicates least information
(H2O2 –> HO) - molecular: gives the actual number of atoms of each element in a molecule of a compound ; indicates the number and type of each atom in the molecule
(H2O2)
structural formula
- a molecular formula that uses lines to represent covalent bonds and shows how atoms in a molecule are connected or bonded to each other, communicates most information about a compound
- indicates how atoms connect
- can also depict the different types of bonds that occur within molecules
- H20: H – O – O – H
- CO2: O = C = O (double bonds)
Ball - and - stick molecular model
- represents atoms as balls and chemical bonds as sticks; how the two connect reflects a molecular shape
- portrays geometry of molecule
- balls are typically color coded:
- carbon = black
- hydrogen = white
- nitrogen = blue
- oxygen = red
Space-filling molecular model
- atoms fill up the space between each other to more closely represent our best estimates for how a molecule might appear if scaled to visible size
- gives the best sense of the relative sizes of the atoms and how they merge together in bonding
Based on what you learned in Chapter 2 about atoms, what part of the atom do you think the spheres in the molecular space-filling models shown in the table below represent? If you were to superimpose a nucleus on one of these spheres, how big would you draw it?
- Each sphere represents the electron cloud of the atom. The nucleus would be too small to see on the same scale.
Ionic compound formulas
- always contain positive and negative ions
- In a chemical formula, the sum of the charges of the positive ions (cations) must equal the sum of the charges of the negative ions (anions)
- the formula of an ionic compound reflects the smallest whole-number ratio of ions
Which metal has the same charge in all of its compounds?
Ans: “Sr”
- Most transition metals can form more than one kind of cation and its charge must then be specified for a given compound
Naming Binary Ionic Compounds Containing a Metal that Forms ONLY ONE type of Cation
- contain only two different elements
- (name of metal cation)(base name of nonmetal anion + -ide)
Ex: KCl: Potassium Chloride
CaO: Calcium Oxide
