Chapter 6: Relationships and Patterns in Chemistry Flashcards
who came up with the idea of conservation of mass?
Antoine Laurent de Lavoisier
who said this: “Nothing is lost, nothing is created, everything is transformed”
Antoine Laurent de Lavoisier
Johann Döbereiner realized he could organize certain elements into groups of _____ which he called ______
three called triads
Antoine Émile Béguyer de Chancourtois was the first to recognize the ________ of elements
periodicity
in what order did Chancourtois organize the elements?
by atomic weight
Julius Lothar Meyer published the periodic table based on the _______ of each element?
valency
John Newlands noticed that some trends were based of off which number? What was the name of this law?
8
law of octaves
Dimitry Mendeleev ordered the periodic table by _______?
molar mass
T or F: Mendeleev left empty spots in his table?
True, he predicted undiscovered elements that would take those places
def: arranging the elements by increasing aotmic mass produced an observable patter in which similar properties repeat on a regular basis, or periodically
periodic law
what were two problems with Mendeleev’s table?
- it didn’t predict the noble gases (they don’t react so it’s hard to discover them)
- it couldn’t locate hydrogen, as it fit in multiple places
who reordered the periodic table based on atomic number?
Henry Moseley
what are the elements 93-118 called?
the trans-uranium elements
def: horizontal rows on the periodic table, where atomic number increases by one and properties gradually change from one end to the other
periods
def: vertical columns on the periodic table, in which elements have similar properties, owing to the similarity of their electron configurations
groups (families)
def: groups 1 & 2 (s block) and 13-18 (p-block) on the periodic table, except hydrogen
main group elements
def: groups 3-12 on the periodic table, encompassing all the metals of the d and f blocks
transition metals
def: two rows of elements generally placed below the main table, comprising the metals of the f block
inner transition metals
def: elements Z = 57 through Z = 71, lanthanum through lutetium
lanthanides
def: elements Z = 89 through Z = 103, actinium through lawrencium
actinides
def: any of an atom’s electrons that can participate in bond formation with other atoms, whether ionically or covalently
valence electron
for transition metals, valence electrons are all those _______ the ________, regardless of their principal quantum number
outside the atom’s noble gas core
def: any of an atom’s electrons that isn’t a valence electron and that doesn’t participate in bond formation
core electron
def: the metallic elements of the periodic table that fall between the transition metals and the metalloids
post-transition metals
def: predictable and regular patterns of cyclical change in elemental properties throughout the periodic table, moving either vertically or horizontally
periodic trends
def: an expression of the size of an atom, representing the typical distance from the centre of it’s nucleus to the boundary of its electron cloud
atomic radius
why can’t we determine the precise size of an atom?
because the electron cloud does not have distinct boundaries
def: an estimate of the size of an atom, based on half the distance between covalently bonded atoms
covalent radius
def: an estimate of the size of a metal atom, based on half the distance between the nuclei and adjacent atoms in a metal lattice
metallic radius
what two factors influence the size of an atom’s electron cloud?
- how many energy shells contain electrons
- the amount, nature and separation of charge within the atom
as the principle quantum number goes up, the number of outermost shells _____ and they get _____ in distance to the nucleus
goes up and they get further away
what force are neutrons held together by?
residual strong force
T or F: adding more electrons and protons increases the amount of opposite charge in the atom, increasing the nucleus’s inward pull on the valence electrons, making atoms smaller across the table
True
def: the repulsive action of inner core electrons on outer valence electrons, effectively reducing the nucleus’s inward pull, causing the atom to increase in size
shielding effect
def: the net positive charge experienced by an electron in a multi-electron atom, representing less than the full nuclear charge as inner electrons repel outer electrons, offsetting some of the nucleus’s inward pull
effective nuclear charge (Zeff)
when metals form cations, what happens to their ionic size?
it’s smaller than it’s atomic radius
when non-metals form anions, what happens to their ionic size?
it’s larger than it’s atomic radius
def: the amount of energy required to remove the most loosely held electron from a gaseous atom to form a cation to increase its positive charge
ionization energy (IE)
generally speaking, each electron is ____ to remove than the last
harder
as Zeff increases, atoms become ______ and electrons become more ____ to remove, causing an ________ in ionization energy
atoms become smaller and electrons become more difficult to remove, causing an increase in ionization energy
def: a chemical property that describes an atom’s (or a group of atoms’) ability to attract electrons towards itself
electronegativity (EN)
def: the change in energy when an atom gains an electron to form an anion, or when an anion gains another electron, increasing its negative charge
electron affinity
the stronger an element attracts electrons, the _____ energy it releases when gaining an electron, making its electron affinity ______
the more energy releases when gaining an electron, making its electron affinity greater
def: a numerical value representing the difference in the electronegativities of two atoms
ΔEN
metals have relatively _____ ionization energies
low
non-metals have relatively _____ electronegativities
high
non-metals have relatively _____ electron affinities
high
an ionic bond will form between a metal and a non metal if their ΔEN is greater than _____
1.7
a covalent bond will form between two non-metals if their ΔEN value is less than _______
1.7
def: a covalent bond between non metal atoms with the same electronegativities, where electron sharing is equal
non polar covalent bond
a non polar covalent bond forms between two non-metals if their ΔEN value between ____ and _____
0 and ~ 0.4
def: a covalent bond between two non-metals in which electron sharing is sufficiently unequal that the bond displays significant and meaningful ionic nature
polar covalent bond
def: the non-integer charge values at the ends of a polar covalent bond, due to the uneven distribution of electron density within the bond
partial ionic charges
def: a simplified diagram that communicates molecular structure using element’s symbol as well as dots and lines
Lewis Structure
which two noble gases form compounds?
xenon and krypton
def: describes an atom’s combining power, often in terms of how many hydrogen atoms it can covalently bond with, or how many chloride anions it can ionically bond with
valency
rather than lattices, covalent compounds form______
separate and distinct molecules
def: any pair of valence electrons that are nonbonding, as atoms don’t share them with other atoms
lone pair
T or F: Lone pairs may form or disperse because of bond formation
True
def: an observational rule in chemistry that says the valence shells of the first-period elements hydrogen and helium can hold a maximum of two electrons, never more
duet rule
which atoms do not obey or exceed the octet rule?
H, He, Be, B, Al
def: an observational rule of thumb in chemistry that says main-group elements from periods 2 to 7 seek to have eight electrons in their valence shell
octet rule
T or F: the central atom in a binary compound is usually the one of lower electronegativity
True
def: covalent bonding between two atoms who share more than two electrons
multiple bonds
def: a configuration of elements from periods 3 to 7, in which their valence shells expand past eight electrons as the central atom, as they can incorporate d orbitals
expanded octet
def: different, but equivalent Lewis structures of the same molecule, showing all the possible double bond locations, connected by a double headed arrow
resonance structures
def: electrons in a molecule, ion or solid metal that aren’t associated with a single atom or covalent bond, allowing them to be covalent to more than two atoms
delocalized electrons
electron delocalization allows the creation of an _________
electrical current
def: a model chemists use to predict a molecule’s geometry based on how many groups of electrons surround the central atom, both bonding electrons and lone pairs
valence shell electron pair repulsion theory
VSEPR
def: a number used in VSEPR theory to predict molecular geometry, that is equal to the number of peripheral atoms plus the number of lone pairs
steric number
how do you find the steric number?
peripheral atoms + lone pairs = steric number
def: the superposition or mixing of atomic orbital wave functions to produce new hybrid orbitals with unique shape and energies
orbital hybridization
def: the strongest type of covalent bond, formed between two atoms when their orbitals overlap head on
sigma bond
def: a second type of covalent bond that is weaker than a sigma bond, formed between two atoms when their p orbitals are parallel and overlap side on
pi bond
def: a vector quantity that expresses a bond’s polarity, showing the separation of opposing charges, and the directionality of that separation (a moment)
bond dipole moment
T or F: A polar bond has a relatively large ΔEN value, producing a bond dipole moment that is not strong
enough to affect behaviour, while a non-polar bond’s ΔEN value produces one that is
False
def: a molecule that has an overall, or net dipole moment, because of it’s bond polarities and its molecular geometry
polar molecule
T or F: Polar molecules must contain polar bonds, but cannot be symmetrical, in both structure and
composition – polar bonds and asymmetrical structure or composition make polar molecules
True
def: the attractive force that exists between the partial positive charge of one polar molecule and the partial negative charge of another
dipole-dipole force
def: an electrostatic attraction that forms between the partially positive hydrogen in a highly polarized bond (usually H-N, H-O, and H-F) and the negative lone pair on a nearby atom
hydrogen bond
def: a weakly attractive force that forms when non polar molecules gain temporary dipole moments
London dispersion forces
