Unit 2 - bonding Flashcards
what is bonding?
-the joining of 2 atoms in a stable arrangement
what happens during bonding?
-elements will gain, share or lose electrons to reach electron configuration of the noble gas closest to them in the periodic table
describe ionic bonds
-the transfer of electrons from one element to another
describe covalent compounds
-the sharing of electrons between two atoms
what is a molecule?
-compound or element containing 2+ atoms joined
what are ions
-charged atoms
-# of protons & electrons in the atom is unequal = not neutral
describe covalent compounds
-two nonmetals combine
-or a metalloid bonds to a nonmetal
describe ionic compounds
-consist of oppositely charged ions that have strong electrostatic attraction for each other
-always*** formed from metal & nonmetal
what are the two types of ions?
-cations
-anions
describe cations
-positively charged ions
-has fewer electrons than protons
-by losing 1-3 electrons, an atom forms a cation w/ a completely filled outer shell of electrons
-metals like Na & Mg form cations
describe anions
-negatively charged ions
-more electrons than protons
-by gaining 1-3 electrons, an atom forms an anion w/ a completely filled outer shell of electrons
-nonmetals like Cl form anions
what is the octet rule?
-main group element is especially stable when it possesses an octet (8) of electrons in its outer shell
-will become the electron configuration of the nearest noble gas
common ions found in the human body
-Ca2+ = bones
-Na+ and K+ = body fluids
-Fe2+ = hemoglobin of the blood
-Cl1- = gastric juices of the stomach & other fluids
-Mg2+ = needed for nerve transmission & muscle control
how to you name ions? give examples
-add suffix ‘ide’
-ex: oxide, sulfide
what must be included when naming compounds w/ transition metals?
include the roman numerals that show which charge of the transition metal is being used
describe the physical properties of ionic compounds
-crystalline solids
-very high melting & boiling points
-when dissolved in water, they separate into cations & anions = increased conductivity of the solution
what is a polyatomic ion?
-cation or anion that contains more than one atom
what is the only known polyatomic cation?
ammonium (NH4+)
carbonate molecular formula
CO3(2-)
hydrogen carbonate molecular formula
HCO3 (-)
acetate molecular formula
CH3CO2 (-)
cyanide molecular formula
CN(-)
nitrate molecular formula
NO3(-)
nitrite molecular formula
NO2(-)
hydroxide molecular formula
OH(-)
phosphate molecular formula
PO4(3-)
sulfate molecular formula
SO4(2-)
sulfite molecular formula
SO3(2-)
what is a molecule
-a covalent compound
-discrete group of atoms held together by covalent bonds
what are unshared e- pairs?
lone pairs, they are unbonded
what does the lewis structure show?
-shows location of valence electrons
how many bonds will H form?
1
how many bonds will C form?
4
how many bonds will N form? & how many lone pairs will it have
3 bonds
1 lone pair
how many bonds will O form & how many lone pairs will it have
2 bonds
2 lone pairs
how many bonds will halogen form & how many lone pairs will it have?
1 bond
3 lone pairs
all amino acids are:
covalent compounds
Lewis structure for polyatomic ions:
-add one electron for each negative charge
-subtract one electron for each positive charge
what is resonance?
-delocalization of electrons
-same arrangement of atoms, different arrangement of electrons
what does delocalization do?
-makes a molecule stable
naming covalent compounds prefixes
-mono
-di
-tri
-tetra
-penta
-hexa
-hepta
-octa
-nona
-deca
what is valence shell electron pair repulsion theory?
either an atom or a lone pair is a group that surrounds an atom
linear molecular shape group & bond angle
-2 groups
-180 degree bond angle
-ex: CO2
trigonal planar molecular shape group & bond angle
-3groups
-120 degree bond angle
-ex: BF3 & H2CO (formaldehyde)
tetrahedral molecular shape group & bond angle
-4 groups
-109.5 bond angle
-ex: CH4 (methane)
trigonal pyramid molecular shape group & bond angle
-4 groups + 1 lone pair
-107 degree bond angle
-ex: NH3 (ammonia)
bent shape molecular shape group & bond angle
-4 groups + 2 lone pairs
-105 degree bond angle
-ex: H2O
what is electronegativity
-the measure of an atom’s attraction for electrons in a bond
-not a complete transfer of electrons == SLIGHTLY negative charges
difference between ionization & electronegativity ?
-ionization is the complete transfer of electrons (formation of anions)
how does electronegativity change across the periodic table?
-across the period = increases
-down the group = decreases
Electronegativity difference:
-0.5 = nonpolar
-0.5-1.9 = polar covalent
-greater than 1.9 = ionic
