Chapter 4: The Periodic Table Flashcards
What four elements did Greek Philosophers believe the universe was made up of?
(4)
- water
- fire
- earth
- air
Who believed the universe was made up of four elements of fire, water, earth and air?
-Greek philosophers
Greek philosophers believed that fire, water, earth and air made up what?
-the universe
What did the theory that the universe was made up of four elements become the basis of?
-chemical theory
What became the basis of chemical theory?
-that the universe was made of four elements
What two scientists made a great contribution to the modern development of our understanding of the idea of an element?
(2)
- Robert Boyle
- Humphry Davy
What did Robert Boyle and Humphry Davy both contribute to?
-the modern development of our understanding of the idea of an element
Who first gave an accurate definition of an element?
-Robert Boyle
Who was Robert Boyle?
-an Irish chemist born in Lismore Castle, Co. Waterford
What did Robert Boyle first give an accurate definition of?
-an element
Who was an Irish chemist born in Lismore Castle, Co. Waterford?
-Robert Boyle
Why is water not an element?
-because it can be split into hydrogen and oxygen
What is formed when elements combine together in chemical reactions?
-a compound
When is a compound formed?
-when elements are combined together
What are combined together to form a compound?
-elements
Some of the most important discoveries in the history of the elements were made by what English chemist?
-Humphry Davy
Who was Humphry Davy?
-an English chemist
What elements did Humphry Davy discover?
6
- potassium
- sodium
- calcium
- barium
- strontium
- magnesium
Potassium, sodium, calcium, barium, strontium and magnesium were discovered by who?
-Humphry Davy
How dud Humphry Davy discover potassium?
-by passing electricity through a compound of potassium
What did Humphry Davy pass through a compound of potassium to discover the element potassium?
-electricity
What did Humphry Davy pass electricity through to discover potassium?
-a compound of potassium
A compound of what was electricity passed through by Humphry Davy to discover potassium?
-a compound of potassium
What four chemists tried to order the elements?
4
-Johann Dobereiner
-John Newlands
Dmitri Mendeleev
-Henry Moseley
Who was Johann Dobereiner?
-a German chemist
Who noticed that the element bromine seemed halfway between those of chlorine and iodine?
-Johann Dobereiner
What did Johann Dobereiner notice?
-he noticed that bromine seemed halfway between those of chlorine and iodine
What did Johann Dobereiner notice about the properties from chlorine to bromine to iodine?
-there was a smooth gradation of properties
What elements did Dobereiner notice a gradation of properties from?
-from chlorine to bromine to iodine
Besides the gradation of properties what did Dobereiner look at in relation to elements?
-the atomic weights of elements
What is the modern name for atomic weight?
-relative atomic mass
What was the relative atomic mass used to be called?
-atomic weight
What did Dobereiner notice about the atomic weight of bromine?
-it was about half way between that of chlorine and iodine
What element did Dobereiner notice the atomic weight was about half way between that of chlorine and iodine?
-bromine
Between iodine and what element did Dobereiner notice the atomic weight of bromine was half way between?
-chlorine
Between chlorine and what element did Dobereiner notice the atomic weight of bromine was half way between?
-iodine
What did Dobereiner call his groups of three elements?
-a triad
Why were Dobereiner’s triads looked on as coincidences that were of little significance?
-few other cases of triads could be found
What resulted when few other cases of Dobereiner’s triads could be found?
-they were looked on as coincidences that were of little significance
Why is Dobereiner’s work important?
-it was the earliest attempt to trace a relationship between properties of the elements and their atomic weights
Who’s work was the earliest attempt to trace a relationship between properties of the elements and their atomic weights?
-Dobereiner
What did Dobereiner attempt to trace a relationship between?
-properties of the elements and their atomic weights
Who was John Newland?
-an English analytical chemist
Who was an English analytical chemist?
-John Newlands
How did Newlands arrange the elements?
-in order of their atomic weights
Who ordered the elements in order of their atomic weights?
-John Newlands
What did Newlands notice when he ordered the elements in increasing atomic weights?
-he noticed that the properties of the elements seemed to repeat with every eight element
Who noticed that the properties of the elements seemed to repeat with every eight element?
-John Newlands
When did Newlands notice the properties of the elements repeated themselves when ordered in increasing atomic weights?
-every eight element
When did John Newland notice that the properties of the element repeated themselves every eight?
-when ordered in increasing atomic weights?
What was missing from Newlands’ table?
-the noble gases
Why were the noble gases missing from Newlands’ table?
-they had not yet been discovered
What did Newland not realise?
-some elements had not yet been discovered
What should Newlands left in his table?
-gaps
What shouldn’t Newlands had done?
-tried to force all the known elements to fit into his table
What did Newlands’ try to do to all the known elements?
-force them into his table
For what elements did Newlands’ Law of Octaves work?
-the first sixteen
What happened after the first sixteen elements in Newlands’ table?
-some of the elements were forced into the wrong groups
What did it mean if Newlands’ Law of Octaves didn’t work?
-there was little or no similarity between a first element and its corresponding eight element
What did it mean if there was little or no similarity between a first element and its corresponding eight element in Newlands’ table?
-it meant his Law of Octaves didn’t work
Why would Newlands’ Law of Octaves not work for the modern Periodic Table?
-the noble gases have been discovered since Newland put forward his law
Who was Dmitri Mendeleev?
-professor of chemistry at the University of St. Petersburg, Russia
Who was a professor of chemistry at the University of St. Petersburg Russia?
-Dmitri Mendeleev
In what way did Dmitri Mendeleev order the elements?
-in order of increasing atomic weight and placed elements with similar properties under each other in groups
Who ordered the elements in increasing atomic weight and placed elements with similar properties under each other in groups?
-Dmitri Mendeleev
What periodic recurrence did Mendeleev notice?
-every eight element had similar properties under each other in groups
How did Mendeleev demonstrate the regular repetition of properties?
-he placed all elements with similar properties in the same vertical column as part of a table
Who placed all elements with similar properties in the same vertical column as part of a table?
-Dmitri Mendeleev
What did Mendeleev demonstrate by placing all elements with similar properties in the same vertical column as part of a table?
-the regular repetition of properties
Why was Mendeleev’s table called the periodic table of elements?
-because the properties of the elements repeated at regular intervals or periodically
What was Mendeleev’s table called because the properties of the elements repeated at regular intervals or periodically?
-the periodic table of elements
What did Mendeleev leave in his table?
-gaps
Who left gaps in his table?
-Mendeleev
Why did Mendeleev leave gaps in his table?
-to make all the known elements fit into the proper group (column)
What did Mendeleev say that the gaps in his table represented?
-they represented elements that had not yet been discovered
What did Mendeleev predict?
-the properties of undiscovered elements
What was eventually found out about Mendeleev’s table?
-the properties predicted by Mendeleev were almost identical to the observed properties
What did Mendeleev do to the order of certain elements?
-reversed them
Why did Mendeleev have to reverse the order of some elements?
-so that each element would be in a group with elements of similar properties
How did Mendeleev make certain elements fall into groups of elements with similar properties?
-by reversing their order
What did Mendeleev realise about the properties of elements?
-the properties were more important than the atomic weights
What two elements did Mendeleev reverse the order of?
2
- iodine
- tellurium
What element was named after Mendeleev?
-mendelevium
Who provided an explanation for why Mendeleev had to revers the order of some elements?
-Henry Moseley
Who was Henry Moseley?
-an English scientist
What did Moseley study?
-the frequencies of the x-rays emitted by atoms of the different elements
What did Moseley study that were emitted by atoms of the different elements?
-x-rays
What x-rays did Moseley study?
-those emitted by atoms of the different elements
What did Moseley discover about the frequencies of the x-rays emitted by atoms of the different elements?
-he found that the frequencies varied with the quantity of positive charge in the nucleus
What did Moseley find varied with the quantity of positive charge in the nucleus?
-the frequencies of the x-rays emitted by atoms of the different elements
What did the frequencies of the x-rays emitted by atoms of the different elements vary with?
-the quantity of positive charge in the nucleus
What did Moseley discover?
-a method of determining the number of protons in the nucleus of an atom
What did Moseley discover a method of doing?
-determining the number of protons in the nucleus of an atom
What did Moseley’s discovery bring about a major improvement in?
-Mendeleev’s table
What did Moseley showed happened when the elements were arranged in order of increasing atomic number?
-that it was not necessary to revers the order of some elements as Mendeleev had to
When did Moseley not have to reverse the order of some elements as Mendeleev had to?
-when the elements were arranged in order of increasing atomic number
What did Moseley’s x-ray studies prove?
-that Mendeleev had been correct in placing tellurium before iodine in spite of the higher atomic weight of tellurium
What did Moseley show happened when the elements were arranged in order of increasing atomic number?
-the elements fall naturally into the correct groups
What did Moseley do to make the elements fall naturally into the correct groups?
-he arranged them in order of increasing atomic order
Who was the man who made the final step from Mendeleev’s Periodic table to the modern Periodic Table?
-Moseley
What did Moseley’s work confirm?
-the position of the elements
How is the way that the elements are arranged differently in the modern periodic table compared to Mendeleev’s?
-in the modern table they are ordered in increasing atomic number while in Mendeleev’s they were arranged in order of increasing atomic weight (relative atomic mass)
What table contains more elements then Mendeleev’s?
-the modern periodic table
What does the modern periodic table have more than of Mendeleev’s?
-elements
Why does the modern periodic table have more elements then Mendeleev’s?
-when Mendeleev constructed his table some elements had not been discovered
About how many elements were in Mendeleev’s table?
-60
Over how many elements are in the modern periodic table?
-100
What is in Mendeleev’s table that are not in the modern periodic table?
-gaps
Why did Mendeleev’s periodic table contain gaps?
-for undiscovered elements
