Chapter 2 - The Periodic Table Flashcards
How were the elements arranged in the early periodic tables?
In order of atomic weight.
Why did Mendeleev leave gaps in his periodic table?
He left gaps for undiscovered elements.
Why do elements in a group have similar chemical properties?
They have the same number of electrons in the highest occupied energy level or outer shell.
Why are the noble gases so unreactive?
Due to their very stable electron arrangements; they have complete outer shells / energy levels.
Why are the alkali metals stored in oil?
To prevent reaction with air.
Why are the elements in group 1 called ‘alkali metals’?
They react with water to produce alkalis or their hydroxide are alkalis.
Name and give the formula of the compound formed when potassium reacts with bromine.
Potassium bromide, KBr
Why do the halogens have low melting and boiling points?
They have small molecules made of pairs of atoms.
How could you show that chlorine is more reactive than bromine?
Add chlorine (water) to a solution of potassium bromide (or other soluble bromide); bromide will be displaced.
Why do metals get more reactive going down a group?
When metals react, their atoms lose electrons; as the atoms get larger there are more occupied energy levels and the electrons in the highest occupied level or outer shell are less strongly attracted by the nucleus and so are lost more easily.
Why is lithium less reactive than sodium?
Lithium’s outer electron is closer to the nucleus and therefore more firmly held.
Where are transition metals found in the periodic table?
In the centre block.
List the ways in which transition elements are different from the element in group 1.
Higher melting points, Stronger, Harder, Denser, Less reactive (with oxygen and water), ions have different charges, coloured compounds, catalysts.
