Periodic Table Flashcards
Compare Mendeleev’s periodic table with the modern periodic table
Mandeleev’s table / Modern table
- Less elements / More elements
- Gaps left for undiscovered elements / No gaps
- In order of atomic weight
/ order of atomic number
What is an element?
It is a substance that cannot be split into simpler substances by chemical means.
What is the periodic table?
A table of the chemical elements arranged in order of increasing atomic number.
Distinguish between elements and compounds
An element is something that cant be divided into simpler substances while compounds can be divided.
State the principle resemblances of elements within each main group, in particular, alkali metals, alkaline earth metals, halogens and noble gases
Group 1 and 2 are highly reactive while group 7 to 8 are inert and unreactive.
Describe the reaction between water and lithium, sodium, and potassium
The water bubbled, fizzed occurred and the sample lit on fire.
Describe by means of the chemical equation the reaction between water and lithium
2Li + 2H20 = 2Li0H + H2
Lithium + Water = Lithium Hydroxide + Hydrogen
Outline the history of the idea of elements, including the contributions of Greeks
- Elements are the basic things of which all others are made.
- The elements are earth, fire, air and water.
Outline the history of the idea of elements, including the contributions of Boyle
- Known as the father of chemistry.
- He proposed that elements are substances are that cannot be divided into smaller substances.
Outline the history of the idea of elements, including the contributions of Davy
- Discovered many elements by electrolysis of salts (For example, potassium and salts).
- Electrolyzed water to find it was made up of hydrogen and oxygen in a 2:1 Ratio.
Outline the history of the idea of elements, including the contributions of Moseley
- He used X-rays to discover the number of protons in each element. i.e atomic number.
- He found that the elements in the periodic table are in order of atomic number.
Outline the contributions of Mendeleev to the structure of the modern periodic table
- Arranged elements in order of atomic weight.
- There were periodic trends in properties.
Why did Mendeleev’s periodic table stick while others didn’t
- He left gaps for missing elements.
- Reversed Te and I.
- Put elements into subsets.
Outline the contributions of Dobereiner to the structure of the modern periodic table
He arranged elements in groups of triads that had similar chemical properties
and if the atomic weight of the middle element was halfway between the other two elements.
Outline the contributions of Newlands to the structure of the modern periodic table
- He arranged elements in order of atomic weight and noticed that every 8th element was similar.
- This was rejected however because it broke down on the 3rd octave due to transition elements and undiscovered elements.
