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What is probably the most useful tool for chemists? |
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______play most important role in determining the physical and chemical properties of an element. |
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Arrangment of elements in the periodic table depends on the ______. |
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What are the four categories for classifying elements based on electron configuration? |
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noble gases, representative elements,transisiton metals, inner transisiton metals |
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What is the group number equal to? |
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the number of electrons in the outermost energy level |
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______are metallic elements with outermost s sublevel and nearby d sublevel contain electrons. |
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Transisiton metals make up ______. |
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Transistion metals are characterized by the addition of electrons in _____.. |
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______are metallic elements with outermost s sublevel and nearby f sublevel generally contain electrons. |
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What are inner transistion metals characterized by? |
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the filling of the f orbital |
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The s block corresponds to the the groups ____and____elements. |
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What each period number represent? |
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Atoms do not have_____and the _____of an atom cannot be directly measured. |
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______is used to estimate atomic radii of crystalline structures |
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For diatomic molecules, what is the radius? |
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1/2 the distance between the nuclei of the two atoms |
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Atomic radius indicates_____. |
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Atomic size generally _____as you move down a group in the periodic table. |
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What are the two competing factors that affect atomic size? |
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Definition
electron shielding and effective nuclear charge |
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Why does electron sheilding tend to increase the atomic radius? |
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Definition
because electrons added to higher energy levels don't feel full force of nuclear charge |
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Outer electrons are _____from the nuclear charge. |
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Why does effective nuclear charge tend to shrink atomic size? |
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because of the attractive force between the nucleus and the electrons |
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What happens to the shielding as electrons are added to higher principle energy levels? |
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the shielding of electrons offsets the increased charge of the nucleus |
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Why are cations smaller than the neutral atoms? |
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Definition
because of the attraction of the nucleus on fewer electrons |
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Why are anions larger than the neutral atom? |
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because the inner electrons shield the extra electron |
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Atomic size generally _____as you move from left to right across the period. |
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The shielding effect is ____across a period. |
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The increased nuclear charge pulls the outermost electrons inward. What does this do? |
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decreases the atomic size |
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The energy required to overcome the nuclear charge and remove an electron from a gaseous atom is called the______. |
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What is first ionization energy? |
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Definition
the energy required to remove the outermost electron is |
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What is second ionization energy? |
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the energy required to remove the second outermost electron |
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What is the main difference between the first and second inonization energies? |
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it easy to remove on electron, but difficult to remove others |
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What two factors affect ionization ergy? |
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Definition
nuclear charge and distance from the nucleus |
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Why does first ionization energy generally decrease down a group? |
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Definition
because as you move down the group, the electrons are farther from the nucleus and more easily removed |
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Why does first ionization energy generally increase from left to right across a period? |
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Definition
because nuclear charge increases and shielding is constant which causes a greater attraction of the nucleus for electrons, making it harder to remove an electron |
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Whether an atom gains or loses an electron affects its______. |
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Why are anions generally larger than the neutal atoms? |
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the nuclear attraction is less for the increased number of electrons |
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____generally increases down the group. |
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From left to right across a period ____ gradually decrease in size. |
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The_____of an element is the tendency of the atoms of the element to attract electrons when bonded to another atom. |
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Where does the electronegativity of representative elements decrease? When does it increase? |
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decreses down the group; increases left to right across the period. |
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When does atomic radius increase? When does it decrease? |
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down a group; down a period |
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What is the difference between a group and a period? |
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a group is the column and a period is the row |
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Which are larger: cations or the neutral atoms from which they form? |
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neutral atoms from which they form |
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What does electronegativity measure? |
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Definition
the ability of a bonded atom to attract electrons to itself |
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When does electronegativity decrease? When does it increase? |
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Definition
down the group; across the period |
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Would halogens have low or high electronegativities? |
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How many orbitals are the 4p energy level? |
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Do electrons pair up in each orbital before filling additional ones? |
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To occupy the same orbital, what must electrons have? |
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Bohr discovered that electrons have fixed amounts of energy, they do not_____energy and cannot fall into the ____. |
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What is a quantam of energy? |
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the amount of energy needed to raise an electron to the next higher level |
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ARe energy levels evenly spaced? |
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When is the electron cloud more dense? |
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Definition
when the probability of finding an electron is high |
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Regions in which electrons are likely to be found are called______. |
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Within each principle energy level, electrons occupy _____. |
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Atomic orbitals are designated with what letters? |
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What shape is the s orbital? What shape is the p orbital? What shape is the d orbital? What shape is the f orbital? |
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spherical; dumbell shaped; clover leaf; very complex |
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What does the principle quantam number tell about electrons? |
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the maximum number of electrons in that principle energy level |
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What letter represents the principle quantam number? |
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How many electrons are in the s sublevel? p? d? f? |
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