The Atom And The Periodic table Flashcards
How many naturally occuring elements are there
92
How are the elements arranged
In order of atomic number
Group
Vertical column in the periodic table
Period
Horizontal row in the periodic table
Who was the founder of the periodic table
Mendaleev
Group 1
The alkali metals
These elements all have one electron in their outer shell.
They’re very reactive as we go down the group.
E.g. Lithium (Li), Sodium (Na), Potassium (K)
Physical properties of alkali metals
They are stored in oil
They can be cut with a knife
They quickly lose their shiny appearance
They have low melting points (easy to melt)
They float on water (releasing hydrogen gas)
Group 2
The alkaline earth metals
These elements all have 2 electrons in their outer shell.
They are not as reactive as alkali metals.
E.g. Berryllium (Be), Magnesium (Mg), Calcium (Ca)
Group 7
The halogens
These elements have 7 electrons in their outer shell.
They are very reactive as they want to gain only 1 electron to have a full outer shell.
E.g. Fluorine (F), Chlorine (Cl), Bromine (Br)
Group 8
The noble gases
These elements all have 8 electrons in their outer shell.
They’re unreactive as they have a full outer shell.
E.g. Helium (He), Neon (Ne), Argon (Ar)
Atomic number
No. of electrons and/ protons
Mass number
The number of protons plus the number of neutrons
Isotopes
Atoms of the same element which have a different number of neutrons
Atom
Smallest part of an element which still has the properties of that element
Basic building blocks
3 sub atomic particles
Protons
Neutrons
Electrons
