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Chem Chap 5 Sec 3
Electron Configuration and Periodic Properties
Question | Answer |
---|---|
The size of an atom is defined by what | the edge of its orbital |
What is one way to express an atom's radius | measure the distance between the nuclei of two identical atoms that are chemically bonded together, then divide this distance by two. |
May be defined asw one-half the distance between the nuclei of identical atoms that are bonded together | atomic radius |
The atomic radii decrease from ________ across a __________ and increase ____________________ | left to right across a period; increase down a group |
The trend to smaller atoms across a period is caused by | the increasing positive charge of the nucleus. |
How can an electron be removed from an atom. | enough energy has to be supplied. Equation is A + energy --> A+ +e- |
What does A+ represent in the energy equation | ion of element A with a single positive charge referred to as a 1+ion |
An atom or group of bonded atoms that has a positive or negative charge | ion |
Any process that results in the formation of an ion is referred to as | ionization |
The energy required to remove one electron from a neutral atom of an element | ionization energy, IE (or first ionization energy IE) |
What is done to avoid influence of nearby atoms on the measurement of ionization | Ionization energies are made on isolated atoms in the gas phase |
Group 1 metals have the __________ first ionization energies in their respective periods | lowest |
What is the major reason for the high reactivity of the Group 1 (alkali) metals | Electron loss |
What group has the highest ionization energies | Group 18 elements, the noble gases, |
True or False: ionization energies of the main-group elements decrease across each period | False |
Increasing nuclear charge is responsible for what | increasing ionization energy and decreasing radii across the periods. |
Does nonmetals have higher ionization energies than metals | Yes |
Among the main groups, ionization energies _______ down the groups | decrease |
The energies for removal of additional electrons from an atom are referred to as | the second ionization energy (IE2), third ionization energy IE3, & so on. |
Each successive electron removed from an ion feels an increasingly stronger effective _____ | nuclear charge (the nuclear charge minus the electron shielding) |
The energy change that occurs when an electron is acquired by a neutral atom is | the atom's electron affinity |
Which element gains electrons most readily | halogens |
What is the major reason for the high reactivities of the Group 17 elements | The ease with which halogen atoms gain electrons |
How do you know that an atom has released energy when they acquired an electron | it will hve a negative valuef |
Why does electrons add with greater difficulty down a group | It is the result of 2 competing factors. 1st - A slight increase in effective nuclear charge down a group, which increased electron affinities. 2nd - an increase in atomic radius down a group, which decreases electron affinities. |
Second electron affinities are positive or negative | All positive |
A positive ion is know as | Cation |
The removal of the highest energy level electrons results in a | smaller electron cloud |
A negative ion is known as | anion |
The formation of a cation always leads to | A decrease in atomic radius |
The formatioin of an anion always leads to | an increase in atomic radius |
Why does the formation of an anion leade to increase in atomic radius | The total positive charge of the nucleus remains unchnged when anelectron is added to an atom or an ion. |
Cations are smaller or larger than atoms | smaller |
Anions are smaller or larger than atoms | larger |
The electrons available to be lost, gained, or shared in teh formation of chemical compounds are referred to as | valence electrons |
Where are valance electrons often located | in incompletely filled main-energy levels. |
For main-group elements, the valence electrons are located where | In teh outermost s and p sublevels |
A measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound | Electronegativity |
What are the least electronegative elements | alkali and alkaline-earth metals |
What are the most electronegative elements | nitrogen, oxygen, and halogens |
What tends to be the movement of Electronegativities across the periodic table | They tend to either decrease down a group or remain about the same |
On the Pauling Scale where are electonegative elements located | The most-electronegative elements are locared in the upper right of the p-block. The least-electronegativity elements are located in teh lower left of the s block. |
The d-block elements are what type of elements | metals |
As the number of electrons in the d sublevel increases, teh radii | increase because of repulsion among the electrons. |
atomic radii of the d-block elements _________ across teh periods | Decrease |
The radii decrease is less than that of the main group elements because the electrons added to the sublevel shield the what | outer electrons from the nucleus |
Ionic radii ____________ down a group | increase |
Ionic radii _______________ across a period for cations and for anions | decrease |
What forms because electrons are lost, gained, or shared between atoms. | Chemical compoundf |
What holds atoms together in chemical compounds | Valence electrons |