Chemistry- Periodic Table

Question 1

Johann Dobereiner (1780-1894)

Answer 1

• observed that elements with similar physical and chemical properties fall into groups of 3 (triads)
• Cl, Br, I & Ca, Sr, Ba
• atomic weight of the middle element is approximately the average of the atomic weights of the other 2 (ex. Li, Na, K)

Question 2

Newland’s Law of Octaves

Answer 2

• John Newlands (1864) arranged the known elements (noble gases were not discovered yet) in increasing order of ATOMIC WEIGHTS
• noted that chemically similar elements occurred in every 8 elements
• called the repeating pattern “Law of Octaves”

Question 3

Mendellev

Answer 3

• first periodic table (1869)
• elements arranged by increasing ATOMIC MASS AND SIMILAR PROPERTIES
• some elements were not arranged by atomic mass but rather by similar properties (Te, I & Ar, K)

Question 4

Mendellev’s Periodic Law

Answer 4

• properties of the elements are the periodic functions of their atomic masses
• left blanks for elements yet to be determined, predicted the characteristics of the element

Question 5

Moseley

Answer 5

• modern periodic table
• arranged elements by increasing ATOMIC NUMBER (1913)
• elements in the same group have the same number of valence electrons, similar properties, and form the same ions

Question 6

Modern Periodic Law

Answer 6

• properties of the elements are the periodic functions of their atomic numbers

Question 7

Groups

Answer 7

vertical columns (18)

Question 8

periods

Answer 8

horizontal rows (7)

Question 9

Alkali Metals

Answer 9

• Group 1 expect hydrogen
• MOST REACTIVE METALS
• very soft, shiny metals
• react violently with air and water
• NEVER FOUND UNCOMBINED
• 1 valence electron

Question 10

Alkaline Earth Metals

Answer 10

• Group 2
• soft, shiny metals
• react with air and water
• rarely found uncombined
• 2 valence electrons

Question 11

Transition Metals

Answer 11

• not as reactive as groups 1/2
• strong, shiny metals
• FORM BRIGHTLY COLORED COMPOUNDS

Question 12

Halogens

Answer 12

• Group 17
• all diatomic
• react violently with other metals (usually metals)
• all 3 phases exist at STP
• 7 valence electrons
• MOST REACTIVE NONMETALS

Question 13

Noble Gases

Answer 13

• all gases
• don’t react under normal circumstances
• 8 valence electrons - very stable
• LEAST REACTIVE ELEMENTS

Question 14

Reactivity

Answer 14

• Across: decreases
• Down: increases
• Cs is the most reactive metal
• F is the most reactive nonmetal

Question 15

Metals

Answer 15

• ductile (roll into wires)
• malleable (flatten out into thin sheets)
• conduct heat and electricity
• shiny luster
• tend to lose electrons
• 2/3 of periodic table

Question 16

Nonmetals

Answer 16

• brittle: break easily
• poor conductors
• no water
• tend to gain electrons
• groups 17 and 18

Question 17

Semi Metals/ Metalloids

Answer 17

• some properties of metals, some properties of nonmetals
• semi conductors
• luster depends on element
• can either gain/ lose electrons
• along staircase

Question 18

Periodic Trends

Answer 18

specific patterns that are present in the periodic table, which illustrate different aspects of a certain element

Question 19

Atomic Radius

Answer 19

• Across: decreases (effective nuclear charge increases so valence electrons are drawn closer to nucleus)
• Down: increases
• 1/2 the distance between the nuclei of identically bonded atoms (measured in pm)

Question 20

First Ionization Energy

Answer 20

• Across: increases (electrons are closer together)
• Down: decreases (electrons further away from nucleus)
• amount of energy (kJ/mol) required to remove the outermost electron (from gaseous atom or ion)
• energy will always be required
• there is a big jump at a point because all the valence electrons are gone and you are digging into a new shell

Question 21

Exceptions in first ionization energy

Answer 21

• when going across, there are decreases caused by electron repulsion

Question 22

Electron Affinity

Answer 22

• Across: increases (nonmetals are on the right), becomes more negative
• Down: decreases, becomes more positive
• the change in energy that occurs when an atom gains an electron (kJ/mol)
• metals tend to lose electrons
• is always a negative #

Question 23

Ionic Radius

Answer 23

• Across: cation decreases, anion decreases
• Down: ionic radius increases
• largest ion is C-4
• cations are smaller than the neutral atom
• anions are larger than the neutral atom (excess electrons cause repulsion)

Question 24

Stable configuration

Answer 24

elements in the S and P block want to attain an octet of electrons

Question 25

Electronegativity (Linus Pauling)

Answer 25

- Across: increases - Down: decreases (metals have low electronegativity- tend to lose electrons) - the ability of an atom in a compound to attract electrons from another atom in a compound - F is the most electronegative element - Cs/ Fr is the least electronegative element

Question 26

Metallic Character

Answer 26

- Across: decrease - Down: increases - how easily an element loses electrons - F is the most nonmetallic element - Cs is the most metallic element