chemical periodicity – Flashcards

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What is probably the most useful tool for chemists?
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the periodic table
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______play most important role in determining the physical and chemical properties of an element.
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electrons
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Arrangment of elements in the periodic table depends on the ______.
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 properties of elements
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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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transition metals
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Transisiton metals make up ______.
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group B elements
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Transistion metals are characterized by the addition of electrons in _____..
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d orbitals
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______are metallic elements with outermost s sublevel and nearby f sublevel generally contain electrons.
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innertransition metals
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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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one a and two a
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What each period number represent?
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principle energy levels
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Atoms do not have_____and the _____of an atom cannot be directly measured.
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definite size; radius
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______is used to estimate atomic radii of crystalline structures
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x-ray diffraction
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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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relative size
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Atomic size generally _____as you move down a group in the periodic table.
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increases
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What are the two competing factors that affect atomic size?
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electron shielding and effective nuclear charge
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Why does electron sheilding tend to increase the atomic radius?
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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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shielded
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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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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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decreases
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The shielding effect is ____across a period.
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constant
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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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ionization energy
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What is first ionization energy?
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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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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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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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;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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ionic size
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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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ionic radius
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From left to right across a period ____ gradually decrease in size.
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cations
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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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electronegativity
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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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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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down the group; across the period
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Would halogens have low or high electronegativities?
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high
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How many orbitals are the 4p energy level?
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three
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Do electrons pair up in each orbital before filling additional ones?
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no
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To occupy the same orbital, what must electrons have?
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opposite signs
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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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nucleus
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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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no
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When is the electron cloud more dense?
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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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atomic orbitals
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Within each principle energy level, electrons occupy _____.
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energy sublevels
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Atomic orbitals are designated with what letters?
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spdf
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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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n
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How many electrons are in the s sublevel? p? d? f?
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2; 6; 10; 14
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