Chapter 3; Ionic and Covalent Compounds Flashcards
atoms are held together by…
chemical bonds
ionic bonds…
form when valence electrons are transferred
covalent bonds…
form when valence electrons are shared
compounds have […] potential energy than the separate atoms that form them
lower
atoms form compounds to attain […] valence energy levels
filled
noble gas atoms have […] valence energy levels and do not form chemical bonds
filled
- don’t react to anything
ionic compounds -
also called salts
- composed of oppositely charged ions
- simplest ionic compounds contain monoatomic ions
what is monatomic ions
when metal atoms transfer electrons to nonmetal atoms
a neutral metal atom [….] forming a positively charged ion, a monatomic cation
loses electron(s)
a neutral nonmetal atom […] forming a negatively charged ion, a monatomic anion
gains electron (s)
Ionic bond
strong electrostatic between oppositely charged cations and anions
what is the strongest type of bond
ionic bond
ionic compounds -
held together by strong attraction of opposite charges
- net charge equal to zero, determines ratio of cations to anions
ratio is reflected in subscripts of the compounds formula unit
charge =
protons - electrons
monatomic cations and anions
- result from transfer of electrons
- unequal numbers of protons and electrons
- have symbol (same as atom) with charge as superscript
what are electrolytes
ions dissolved in water to conduct electricity
what are the exceptions to gaining or loosing electrons
Beryllium, Be
Boron, B
groups 1A, 2A, 3A are
cations (loose all their valence electrons)
cation charge = group number
Group 4A Metal and Transition Metal Cations
- don’t always lose all their valence electrons. charge is less predictable
- if it loses a variable number of electrons to form more than one ionic charge, use Roman numeral in name
-
Only elements with variable charges have roman numerals in name
(Ag + Zn exceptions)
iron can loose
2 or 3 electrons
groups 5A, 6A, and 7A anions nonmetals gain…
enough electrons to fill valence energy level
monatomic groups 5A, 6A, and 7A anions names use the name of the element with an…
- ide and +ion
writing the formula unit for an ionic compound
- list cation symbol, then anion symbol
- subscripts indicate lowest, whole-number ratio
- sum of charges on cations and anions must equal zero
writing the name from the formula
- name the cation
- name the anion
- subscript information is NOT included
CaBr2 is Calcium Bromide - use roman numerals to indicate the charge of ions of metals that can exist in more than one form
polyatomic ions…
derive from molecules, not atoms
- contain one or more covalent bonds
- contain an unequal number of protons and electrons
- each has a unique name, formula, and charge
- molecule that has gained or lost valence electrons and therefore has a charge
acetate
C ₂H ₃O₂ (1 neg charge)
carbonate
CO₃²⁻
cyanide
CN (-1 charge)
dihydrogen phosphate
H(subscript 2)PO(subscript 4) (-1 charge)
Hydrogen carbonate (bicarbonate)
HCO(subscript 3) (-1 charge)
hydrogen phosphate
HPO(subscript 4) (-2 charge)
Hydroxide
OH (-1 charge)
hypochlorite
ClO (-1 charge)
nitrate
NO(subscript 3) (-1 charge)
nitrite
NO(subscript 2) (-1 charge)
phosphate
PO(subscript 4) (-3 charge)
sulfate
SO(subscript 4) (-2 charge)
sulfite
SO(subscript 3) (-2 charge)
ammonium
NH(subscript4) (+1 charge)
hydronium
H(subscript 3)O (+1 charge)
writing formula units for ionic compounds containing polyatomic ions
- same procedure as for monatomic ions
- enclose polyatomic ion in parentheses if a subscript is need
naming ionic compounds containing polyatomic ions
- name the cation
- name the anion
- use the name of the polyatomic ion
covalent compounds…
composed of two or more nonmetal atoms joined by covalent bonds
certain elements exist as molecules, the […] elements
diatomic
e.g. H2, N2, O2, F2
2 = subscripts
a […] is a type of covalent bond formed when two atoms share two valence electrons, typically contributed by each atom
single bond
in molecular formulas; specify the [..] in each molecule as subscripts, usually in alphabetical order
number of each type of atom
naming simple binary compounds
- name the first element, then name the second element change the ending to -ide
- insert prefixes indicating the number of each atom type
- mono- prefix used only for the second element
- N(sub 2)O is dinitrogen monoxide, whereas NO is nitrogen monoxide
mono
1
di
2
3
tri
4
tetra
5
penta
6
hexa
what makes a compound ionic
metal with nonmetal bond
molecular formula and chemical structures -
- do show number and type of atoms in a molecule
- do NOT show how atoms are arranged or the type of chemical bonds in the molecule
- chemical structures show how atoms are arranged and the type of chemical bonds in the molecule
lewis dot structures…
account for all valence electrons present in the molecule
octet rule…
bonds form between atoms to fill valence energy levels (usually eight electrons)
- hydrogen = exception b/c only needs two electrons
how many bonds are needed for groups 4A - 7A
4A - four for octet
5A - 3 bonds
6A - 2 bonds
7A - 1 bond
nonbonding pair
2 electrons (dots)
bonding pair
2 electrons (line)
single bond…
one pair of shared electrons
double bond…
two shared pairs
triple bond…
three shared pairs
how many bonding and nonbonding pairs does Carbon, C have?
4 bond
0 nonbonding
how many bonding and nonbonding pairs does Nitrogen, N and Phosphorus, P have
3 bond
1 non bond
how many bonding and nonbonding pairs does Oxygen, O and Sulfur, S have
2 bond
2 nonbonding
how many bonding and nonbonding pairs does Halogens, F, Cl, Br, I have
1 bond
3 nonbond
how many bonding and nonbonding pairs does Hydrogen, H
1 bond
0 nonbond
steps for writing a lewis dot structure from a molecular formula
- determine the total number of valence electrons the molecule
- determine the central atom and place a single bond between the central atom and each atom bonded to it
- calculate the number of remaining valence electrons and distribute them as nonbonding pairs (outer atoms first, then the central atom) to fulfill octets
- if central atom is short of an octet, turn nonbonding pairs of electrons bonds to make double or triple bonds
expanded octet…
period 3 elements can have more than eight electrons in valence energy level
