Matter, Chemical Trends & Bonding Flashcards
Terminology and Concepts
isotopes
different versions of an element where their atomic mass differs
contains different amounts of neutrons
average atomic mass (AAM)
average mass of an element
measure in u
isotopic abundance
a percentage based on how often a particular isotope occurs in nature
isotopic abundance must total to 100%
effective nuclear charge (zeff)
describes the attraction between valence electrons and the nucleus of an atom/ion
more protons measn stronger zeff ∴ greater attraction
shielding effect (S.E)
causes a decrease in zeff due to filled orbitals/rings between the nucleus and its valence electrons
atomic radius/size
the distance between the nucleus and its valence electrons
stronger zeff = smaller radius
ionization energy (I.E)
the energy required to remove electrons to create cations
* greater zeff greater IE needed to remove electrons
general equation: A + energy → A+ + e-
electron affinity (E.A)
is the amount of energy an atom is willing to give up or realease in order to gain electrons
* closer to octet = more energy willing to give
* more filled orbitals = less energy willing to give
* group 18 no E.A
general equation: J + e- → J- + energy
electronegativity (EN)
the ability of an atom to attract electrons in a bond
found on periodic table
ionic bonding
- occurs between metal and non-metal
- metal transfers (loses) electrons
- 1.7 < EN < 3.3
must check EN for metalloids (Si, Ge, As, Sb, Te, Po)
covalent bonding
- occurs when two non-metals combine by sharing electrons
non-polar covalent bond
type of covalent bond
- equal sharing of electrons
- 0 < EN < 0.4
polar covalent bond
type of covalent bond
- unequal sharing of electrons
- 0.4 < EN < 1.7
polarity
the direction in which electrons are attracted to (“pulled”)
dipole
represents the direction of polarity
pulled from lower EN to higher EN
intramolecular forces of attraction
- describes the type of attraction between two atoms
1. non-polar covalent
2. polar covalent
3. ionic
intermolecular forces of attraction
describes the type of attraction between two (or more) compounds
ion-ion attraction
intermolecular forces of attraction
attraction between two ionic compounds
recall: positive attractions negative
ion-dipole attraction
intermolecular forces of attraction
attraction between an ionic compound and a polar compound
hydrogen bond
strong type of dipole-dipole bond
intermolecular forces of attraction
occurs between a hydrogen (already bonded to N,O, or F) in on compound and a nitrogen, oxygen or fluorine (already bonded to it) or another compounds
dipole-dipole attraction
intermolecular forces of attraction
attraction between two (or more) polar compounds
ion-induced dipole attraction
intermolecular forces of attraction
attraction between an ionic compound and a non-polar compound
induction: causes e- to attract/repel within nonpolar compound
dipole-induced dipole attraction
intermolecular forces of attraction
occurs between a polar compound and a non-polar compound
london dispersion force
intermolecular forces of attraction
occurs between two non-polar compounds
very temporary attraction only if electrons are “perfectly” aligned
