C2- The periodic table Flashcards
How is the modern periodic table ordered?
by atomic number
How were the early lists of elements ordered?
by atomic mass
Why did Mendeleev swap the order of some elements?
to group them by their chemical properties
Why did Mendeleev leave gaps in his periodic table?
leave room for elements that had not yet been discovered
Why do elements in a group have similar chemical properties?
have the same number of electrons in their outer shell
Where are metals and non-metals located on the periodic table
Metals to the left
Non-metals to the right
What name is given to the group 1 elements
alkali metals
How does the reactivity of the alkali metals change down the group?
increases
Why does the reactivity of alkali metals increase down the group?
they are larger atoms, so the outermost electron is
further from the nucleus, meaning there are weaker
electrostatic forces of attraction and more shielding
between the nucleus and outer electron, and it is easier
to lose the electron
What name is given to the group 7 elements
halogens
How do the melting points of the halogens change down the group?
increase
How does the reactivity of halogens change down the group?
decreases
Why does the reactivity of halogens decrease down the group?
they are larger atoms, so the outermost shell is
further from the nucleus, meaning there are weaker
electrostatic forces of attraction and more shielding
between the nucleus and outer shell, and it is harder to
gain an electron
What is a displacement reaction?
a reaction where the more reactive element takes the place of a less reactive element.
What name is given to the group 0 elements?
noble gases
Why are the noble gases inert?
they have full outer shells so do not need to lose or gain electrons
How do the melting points of the noble gases change down the group?
increase
