Periodic Table

Question 1

Who developed the periodic table

Answer 1

Johan Doberiener

Question 2

Dobereiner’s Law of Triads

Answer 2

• The development of the periodic table begins with
  German chemist Johann Dobereiner (1780-1849)
  who grouped elements based on similarities.
• Dobereiner noticed the same pattern for the alkali metal
  triad (Li/Na/K) and the halogen triad (Cl/Br/I).
• In 1829 Dobereiner proposed the Law of Triads: Middle
  element in the triad had atomic weight that was the
  average of the other two members.

Question 3

Newlands’ Law of Octaves

Answer 3

• John Newlands, an English chemist,
  wrote a paper in 1863 which classified
  the 56 established elements into 11
  groups based on similar physical
  properties, noting that many pairs of
  similar elements existed which differed
  by some multiple of eight in atomic
  weight.
• In 1864 Newlands published his version
  of the periodic table and proposed the
  Law of Octaves (by analogy with the
  seven intervals of the musical scale). This
  law stated that any given element will
  exhibit analogous behaviour to the eighth
  element following it in the table.

Question 4

Mendeleev’s Periodic Table

Answer 4

• Dimitri Mendeleev (1860s)
  arranged known elements in a
  table, according to atomic mass
• properties of elements repeated
  in a pattern of regular intervals
  (periodically)
• left gaps in table wherever there
  was a break in properties
• table could be used to predict
  physical and chemical properties
  of unknown elements based on
  properties of known elements –
  made Mendeleev famous!

Question 5

Henry Moseley and Atomic Numbers

Answer 5

• Henry Moseley published the results of
  his measurements of the wavelengths of
  the x-ray spectral lines of a number of
  elements which showed that the
  ordering of the wavelengths of the x-ray
  emissions of the elements coincided
  with the ordering of the elements by
  atomic number.
• With the discovery of isotopes of the
  elements, it became apparent that
  atomic weight was not the significant
  player in the periodic law as Mendeleev,
  Meyers and others had proposed.
• The properties of the elements varied
  periodically with atomic number.

Question 6

Modern Periodic Table

Answer 6

• arranges elements according to increasing
  atomic number (number of protons)

Question 7

natural elements

Answer 7

– atomic number 1 to 92
– exist naturally on Earth

Question 8

synthetic/man made elements

Answer 8

– have been made by scientists
– atomic number greater than 93
to 116

synthetic element
(number 112)
produced from the
fusion

eg.Ununbium is a

Question 9

Classes of Elements in the Periodic
Table

Answer 9

metals (left side)
nonmetals (right side)
metalloids (along diagonal “staircase” line)

Question 10

METAL Properties

Answer 10

• hard
• shiny
• malleable
• ductile
• good conductor (of heat and electricity)
• solid (except mercury, which is a liquid)

Question 11

NONMETAL Properties

Answer 11

• not shiny
• not malleable
• not ductile
• dull
• brittle
• poor conductor (of heat and electricity)
• some gases, some solids (except bromine,
  which is a liquid)

Question 12

METALLOID Properties

Answer 12

• shares some properties with metals and some
  properties with nonmetals
• possibly shiny
• solid
• brittle
• silicon and germanium are semi-conductors

Question 13

what is Boron used for (B)

Answer 13

Boron: Used as an insecticide
and used for killing rodents.

Question 14

What is sliicon used for (Si)

Answer 14

Silicon: Used in making
computer chips.

Question 15

what is germanuim used for ( Ge)

Answer 15

Germanium: First electronic
semi-conductor.

Question 16

what is arsenic used for (As)

Answer 16

Arsenic: A poison, the one
used to kill Napoleon.

Question 17

TITANIUM

Answer 17

• Parts of the Guggenheim Museum in Bilbao,
  Spain, are made of titanium panels.
• Strong and lightweight, titanium is also used
  for body implants.

Question 18

ALUMINUM

Answer 18

• Aluminum is an
  excellent
  conductor of heat.
• Here, an
  aluminum plastic
  laminate is used
  to retain the body
  heat of a newborn
  baby.

Question 19

TUNGSTEN

Answer 19

• Tungsten has been used
  as a filament in older
  light bulbs.
• Due to its high melting
  point and electrical
  conductivity, tungsten is
  used in electrical
  electronic industries, as
  well as in alloys with
  other metals.

Question 20

GOLD

Answer 20

• Gold’s resistance to corrosion and its ability
  to reflect infrared radiation make it an
  excellent coating for space vehicles.
• The electronic box
  on the six-wheel
  Sojourner Rover,
  part of NASA’s
  Pathfinder 1997
  mission to Mars, is
  coated with gold

Question 21

LEAD

Answer 21

• Because lead has a high density, it is a good
  barrier to radiation.
• Dentists drape lead aprons on patients before
  taking X rays of the patient’s teeth to reduce
  radiation exposure.

Question 22

AMERICIUM

Answer 22

• Named after America,
  where it was first
  produced, americium is
  a component of this
  smoke detector.
• It is a radioactive metal
  that must be handled
  with care to avoid
  contact.

Question 23

what is a period

Answer 23

• a horizontal row of elements in the periodic
  table
• number 1 to 7

Question 24

what is a group

Answer 24

• a vertical column of elements in the periodic
  table
• number 1 to 18
• a.k.a. “family” because
  elements in a group
  have very similar
  physical and chemical
  properties

Question 25

Main Groups

Answer 25

Group 1 Alkali Metals Group 2 Alkali Earth Metals Group 17 Halogens Group 18 Noble Gases