MCAT General Chemistry exam |Questions
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Groups - ✔️✔️-columns
-elements in the same group have the same valence shell electron configuration
Three types of elements - ✔️✔️metals, nonmetals, and metalloids
Metals - ✔️✔️-shiny (lustrous), conduct electricity well, and are malleable (hammered into
shapes) and ductile (drawn into wires)
-found on the left side and middle of the PT
Nonmetals - ✔️✔️-dull, poor conductors of electricity, and are brittle
-found on right side of the PT
Metalloids - ✔️✔️-aka semimetals
-possess characteristics of both metals and nonmetals
-found in a stair-step pattern starting with boron (B)
Effective nuclear charge - ✔️✔️-Zeff
-the net positive charge experienced by electrons in the valence shell and forms the foundation
for all periodic trends
-increases from left to right across period, with little change in value from top to bottom in a
group
-as principle quantum numbers increase down the column, the valence electrons are
increasingly separated from the nucleus
,Atomic radius - ✔️✔️-one-half of the distance between the centers of two atoms of an element
that are briefly in contact with each other
-decreases from left to right, increases from top to bottom
Ionic radius - ✔️✔️-the size of a charged species
-largest nonmetallic ionic radii and smallest metallic ionic radii exist at the metalloid boundary
-cations are generally smaller than corresponding neutral atom
-anions are generally larger than corresponding neutral atom
Ionization energy - ✔️✔️-aka ionization potential
-the amount of energy necessary to remove an electron from the valence shell of a gaseous
species
-increases from left to right and decreases from top to bottom
-removing an electron is an endothermic process
Active metals - ✔️✔️elements in groups IA and IIA, such as lithium and beryllium, with very low
ionization energies
Electron affinity - ✔️✔️-the amount of energy released when a gaseous species gains an electron
in its valence shell
-increases from left to right, and decreases from top to bottom
-exothermic process
Electronegativity - ✔️✔️-a measure of the attractive force of the nucleus for electrons within a
bond
-increases from left to right, and decreases from top to bottom
Most and least electronegative elements - ✔️✔️Cs=largest, least electrongeative, lowest
ionizaton energy, least exothermic electron affinity
,F=smallest, most electronegative, highest ionization energy, most exothermic electron affinity
Alkali metals - ✔️✔️-Group IA
-typically take on oxidation state of +1 and prefer to lose an electron to achieve a noble gas-like
configuration
-most reactive metals along with alkaline earth metals
Alkaline earth metals - ✔️✔️-Group IIA
-take on oxidation state of +2 and can lose two electrons to achieve noble gas-like
configurations
Chalcogens - ✔️✔️-Group VIA
-eclectic group of nonmetals and metalloids
-take on oxidation state of -2 or +6 (depending on whether nonmetals or metalloids,
respectively) in order to achieve noble gas configuration
-biologically important
Halogens - ✔️✔️-Group VIIA
-highly reactive nonmetals with seven valence electrons
-typically take on oxidation state of -1 and prefer to gain an electron to achieve noble gas-like
configuration
-highest electronegativities
Noble gases - ✔️✔️-Group VIIIA
-have fully filled valence shell in standard state and prefer not to give up or take on additional
electrons
-have very high ionization energies and (for He, Ne, and Ar) virtually nonexistent
electronegativities and electron affinities
, Transition metals - ✔️✔️-B
-considered to be metals, and have low electron affinities, low ionization energies, and low
electronegativities
-take on multiple oxidation states, which explains their ability to form colorful complexes with
nonmetals in solution and their utility in certain biological systems
Molecules - ✔️✔️smallest polyatomic unit of an element or compound that exists with distinct
chemical and physical properties
Chemical bonds - ✔️✔️-strong attractive forces
-fomred via the interaction of the valence electrons of the combining atoms
Octet rule - ✔️✔️an atom tends to bond with other atoms so that it has eight electrons in its
outermost shell, forming a stable electron configuration similar to that of the noble gases
Incomplete octet - ✔️✔️stable with fewer than eight electrons and include H, He, Li, Be, and B
Expanded octet - ✔️✔️stable with more than eight electrons and include all elements in period 3
or greater
Odd number of electrons - ✔️✔️any molecule with odd number of valence electrons cannot
distribute those electrons to give eight to each atom
Ionic bond - ✔️✔️-formed via the transfer of one or more electrons from an element with a
relatively low ionization energy to an element with a relatively high electron affinity
-occur between elements with large differences in electronegativity (∆EN>1.7), usually between
metals and nonmetals
-electrostatic attraction between ions causes them to remain in close proximity, forming the
bond
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Groups - ✔️✔️-columns
-elements in the same group have the same valence shell electron configuration
Three types of elements - ✔️✔️metals, nonmetals, and metalloids
Metals - ✔️✔️-shiny (lustrous), conduct electricity well, and are malleable (hammered into
shapes) and ductile (drawn into wires)
-found on the left side and middle of the PT
Nonmetals - ✔️✔️-dull, poor conductors of electricity, and are brittle
-found on right side of the PT
Metalloids - ✔️✔️-aka semimetals
-possess characteristics of both metals and nonmetals
-found in a stair-step pattern starting with boron (B)
Effective nuclear charge - ✔️✔️-Zeff
-the net positive charge experienced by electrons in the valence shell and forms the foundation
for all periodic trends
-increases from left to right across period, with little change in value from top to bottom in a
group
-as principle quantum numbers increase down the column, the valence electrons are
increasingly separated from the nucleus
,Atomic radius - ✔️✔️-one-half of the distance between the centers of two atoms of an element
that are briefly in contact with each other
-decreases from left to right, increases from top to bottom
Ionic radius - ✔️✔️-the size of a charged species
-largest nonmetallic ionic radii and smallest metallic ionic radii exist at the metalloid boundary
-cations are generally smaller than corresponding neutral atom
-anions are generally larger than corresponding neutral atom
Ionization energy - ✔️✔️-aka ionization potential
-the amount of energy necessary to remove an electron from the valence shell of a gaseous
species
-increases from left to right and decreases from top to bottom
-removing an electron is an endothermic process
Active metals - ✔️✔️elements in groups IA and IIA, such as lithium and beryllium, with very low
ionization energies
Electron affinity - ✔️✔️-the amount of energy released when a gaseous species gains an electron
in its valence shell
-increases from left to right, and decreases from top to bottom
-exothermic process
Electronegativity - ✔️✔️-a measure of the attractive force of the nucleus for electrons within a
bond
-increases from left to right, and decreases from top to bottom
Most and least electronegative elements - ✔️✔️Cs=largest, least electrongeative, lowest
ionizaton energy, least exothermic electron affinity
,F=smallest, most electronegative, highest ionization energy, most exothermic electron affinity
Alkali metals - ✔️✔️-Group IA
-typically take on oxidation state of +1 and prefer to lose an electron to achieve a noble gas-like
configuration
-most reactive metals along with alkaline earth metals
Alkaline earth metals - ✔️✔️-Group IIA
-take on oxidation state of +2 and can lose two electrons to achieve noble gas-like
configurations
Chalcogens - ✔️✔️-Group VIA
-eclectic group of nonmetals and metalloids
-take on oxidation state of -2 or +6 (depending on whether nonmetals or metalloids,
respectively) in order to achieve noble gas configuration
-biologically important
Halogens - ✔️✔️-Group VIIA
-highly reactive nonmetals with seven valence electrons
-typically take on oxidation state of -1 and prefer to gain an electron to achieve noble gas-like
configuration
-highest electronegativities
Noble gases - ✔️✔️-Group VIIIA
-have fully filled valence shell in standard state and prefer not to give up or take on additional
electrons
-have very high ionization energies and (for He, Ne, and Ar) virtually nonexistent
electronegativities and electron affinities
, Transition metals - ✔️✔️-B
-considered to be metals, and have low electron affinities, low ionization energies, and low
electronegativities
-take on multiple oxidation states, which explains their ability to form colorful complexes with
nonmetals in solution and their utility in certain biological systems
Molecules - ✔️✔️smallest polyatomic unit of an element or compound that exists with distinct
chemical and physical properties
Chemical bonds - ✔️✔️-strong attractive forces
-fomred via the interaction of the valence electrons of the combining atoms
Octet rule - ✔️✔️an atom tends to bond with other atoms so that it has eight electrons in its
outermost shell, forming a stable electron configuration similar to that of the noble gases
Incomplete octet - ✔️✔️stable with fewer than eight electrons and include H, He, Li, Be, and B
Expanded octet - ✔️✔️stable with more than eight electrons and include all elements in period 3
or greater
Odd number of electrons - ✔️✔️any molecule with odd number of valence electrons cannot
distribute those electrons to give eight to each atom
Ionic bond - ✔️✔️-formed via the transfer of one or more electrons from an element with a
relatively low ionization energy to an element with a relatively high electron affinity
-occur between elements with large differences in electronegativity (∆EN>1.7), usually between
metals and nonmetals
-electrostatic attraction between ions causes them to remain in close proximity, forming the
bond
