C2 The periodic table Flashcards
Why was Mendeleev’s periodic table accepted by the scientific community?
Because he left gaps for elements which were later discovered and matched his predictions
Why are noble gases unreactive?
Because they have full outer shells
Do the atoms of metals tend to lose electrons or gain electrons?
Lose electrons (and form positive ions)
Do the atoms of non-metals tend to lose electrons or gain electrons?
Gain electrons (and form negative ions)
Are alkali metals very reactive?
Yes
What state are alkali metals at room temperature?
Soft solids
What is the trend of melting and boiling points in the alkali metals?
Low, decrease going down the group
Why do Lithium, Sodium and Potassium float on water?
Because they have low densities
What is the trend of reactivity in the alkali metals?
The reactivity increases going down the group
What are the halogens?
Non-metallic elements that exist as small molecules made up of pairs of atoms
What is the trend of reactivity in the halogens?
The reactivity decreases going down the group
What can a more reactive halogen do to a less reactive one?
Displace it from a solution of one of its salts
Why does reactivity increase going down group 1?
Because the outer electron is less strongly attracted to the nucleus as the number of shells in between said electron and nucleus increases as you go down the group, meaning that the electron can be lost much easier and quicker
Why does reactivity decrease going down group 7 (halogens)?
Because the attraction of the outer shells to the nucleus decreases as the number of shells increase going down the group, meaning that it is harder to gain an electron
How do the transition elements compare to the alkali metals?
They have high melting points and densities. They are stronger and harder but less reactive
