grouped elements with similar properties first periodic table created by
Dmitri Mendeleev
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who arranged periodic table together in order of increasing atomic number?
Henry Moseley
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metals are located on which side of periodic table
left (exception:hydrogen)
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characteristics of metals
-ductile -malleable good conductors of heat and electricity high melting points (except for Mercury)
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nonmetals located on
right side of periodic table (C, P, S I ,Se=solids at room temp)
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metalloids
staircase seperates nonmetals from metals
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if element is a good conductor of heat but brittle it is
a metalloid
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alkali metals melting point
-lowest melting point
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which one can you cut w a knife?
alkali metals
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moving down a group, metallic character becomes stronger for?
alkali metals and alkaline earth metals
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alkaline earth metals melting point?
higher melting point than alkali metals
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what is very reactive with water?
alkaline earth metals
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what is the exception with reaction of water with these 2 elements?
Be=no reaction Mg= will react with steam
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transition metals melting point is
high melting point and much less reactive than alkali metals
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characteristics of transition metal
ductile and malleable
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moving down group for transition metal, metallic character becomes
stronger
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oxygen group metallic character increases going down or decreases
increases
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O=
nonmetal
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Te=
metalloid
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Po=
metal
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halogens are the most reactive...
nonmetals
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which is the most reactive nonmetal for the halogens?
Flourine (F)
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what is reactivity based on for halogens?
7 electrons in outer shell, wanting one more electron to fill octet
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are noble gases reactive?
no because s and p shells are compeltely filled in
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lanthinides + actinides are
metals, very reactive
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are lanthinides or actinides radioactive?
actinides
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Zeff is
charge experienced by an electron on a many-electron atom
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going across periodic table, Zeff
increases
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why does Zeff increase going across a period?
because more valence e- added while screening e- does not increase
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going down periodic table, Zeff
increases slightly
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put following elements in order of increasing Zeff: Be, Ca, Sr, Mg
Be
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atomic radii across table
decreases
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why does atomic radius decrease going across table?
bc as more e- added, nucleus pulls those e- closer, decreasing atom size
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going down table, atomic radius
increases
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why does atomic radius increase going down periodic table?
bc more shells added going down, increasing atom size
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put elements in order of increasing atomic radius: Be, C, K, Ca
C
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Ionization energy is
energy required to remove one e- from a neutral atom of element
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when e- removed or gained we create an
ion
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across table IE
increases
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why does IE increase across table?
bc more energy is required to remove e-
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going down table, IE
decreases
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why does IE decrease going down table?
bc less energy required to remove an e- bc they are farther from the nucleus
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removing more e-, increases or decreases IE?
increases
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put following elements in order according to IE: Be, C, K, Ca
K
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Electron affintiy is
energy change when one e- is added to a neutral atom of element (Na + e-) = Na-
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moving across, EA
increases
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why does EA increases across period
increase in # of val e- , elements want to have full octet
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going down, EA
decreases
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why does EA decrease going down a group?`
e- further away from nucleus due to increasing atomic radii
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which element has highest e- affintiy?
fluorine
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put elements in order of increasing EA: Be, C, K, Ca
K
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Ionic Radii has
cation (+) anion (-)
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is a cation bigger than its parent atom?
smaller bc e- removed making e- cloud smaller
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is anion bigger than its parent atom?
bigger bc e- gained, increasing radius
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which of following atoms or ions bigger? Ca or Ca^2+
Ca
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S or S^- bigger?
S^-
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Electronegativity is
ability of atom in chemical compound to attract e-
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most electronegative compound
Flourine
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moving across table, electrongeativty
increases
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why does electroneg increase across table
charge on nucleus increases which attracts more e-
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moving down table, electroneg
decreases
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why does electroneg decrease going down table
bc size of atom increases , so e- cannot be pulled as close
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put following elements in order of increasing electroneg: F, As, Sn, S
Sn
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Octet Rule
atoms lose/gain/share e- to get to 8 val e-
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if F wants to get 8 val e- how many e- does it need to gain?
1
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if Mg wants to get 8 val e- how many e- does it need to lose?
2
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smallest atomic radius=
noble gases
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which group have largest atomic radii
metals
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atomic radii cannot be measured directly bc electron cloud surrounding the nucleus does not have a clearly defined (charge, mass, outer edge, probability)
outer edge
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atom becomes negatively charged when an electron is
gained
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difference between electroneg + ea
ea gains e- electroneg ability to attract e- from other atom