Chapter 2 - Structure of Atoms & the Periodic Table
Atom: The basic structural unit of an element
The smallest unit of an element that retains the chemical properties of an element
Atoms Consist of 3 primary particles:
Electrons
Protons
Neutrons
Nucleus: Small, dense positively charged region in the centre of the atom
Protons: Positively Charged
Neutrons: Uncharged or Neutral
Symbolic Representation of an Element
1
,Atomic Number (Z): Number of protons in an atom
Mass Number (A): Sum of number of protons & Neutrons
Hydrogen is the only element that doesn’t have a neutron, it has 1 proton & 1 electron
Hydrogen is the only element in the periodic table who's Atomic Number = Mass
Number
The Periodic Law & the Periodic Table
Dmitri Mendeleev was the first to start working on the periodic table, grouping them
together based on their properties and arranging them by their increasing atomic masses
2
, The modern periodic table arranges elements based on their increasing atomic number
Periodic Trend: Similarity of the properties of the elements that are grouped (Same
column) together despite the difference in their atomic number
Non-metals have higher electronegativity than hydrogen
So hydrogen is a cation when with non-metals
Metals have lower electronegativity than hydrogen
So hydrogen is an anion when with metals
Parts of the Periodic Table
Period: The horizontal rows
Group (Families): Columns of elements
Elements in the same family share a lot of the same properties
Classification of Elements
3
Atom: The basic structural unit of an element
The smallest unit of an element that retains the chemical properties of an element
Atoms Consist of 3 primary particles:
Electrons
Protons
Neutrons
Nucleus: Small, dense positively charged region in the centre of the atom
Protons: Positively Charged
Neutrons: Uncharged or Neutral
Symbolic Representation of an Element
1
,Atomic Number (Z): Number of protons in an atom
Mass Number (A): Sum of number of protons & Neutrons
Hydrogen is the only element that doesn’t have a neutron, it has 1 proton & 1 electron
Hydrogen is the only element in the periodic table who's Atomic Number = Mass
Number
The Periodic Law & the Periodic Table
Dmitri Mendeleev was the first to start working on the periodic table, grouping them
together based on their properties and arranging them by their increasing atomic masses
2
, The modern periodic table arranges elements based on their increasing atomic number
Periodic Trend: Similarity of the properties of the elements that are grouped (Same
column) together despite the difference in their atomic number
Non-metals have higher electronegativity than hydrogen
So hydrogen is a cation when with non-metals
Metals have lower electronegativity than hydrogen
So hydrogen is an anion when with metals
Parts of the Periodic Table
Period: The horizontal rows
Group (Families): Columns of elements
Elements in the same family share a lot of the same properties
Classification of Elements
3
