Atomic Structure
Exploring the atomic world
Element:
Elements are pure and simple substances consisting of one type of atom.
For example: Sodium (Na), Magnesium (Mg), Uranium (U), Bromine (Br).
Compound:
Compounds are pure substances as well, consisting more than one types of atoms bonded together.
For example: NaCl (Sodium Chloride), CaCo3 (Calcium Carbonate), HCl (Hydrogen Chloride)
Mixture:
Mixtures are two or more different kinds of substances that are not chemically combined together.
Atomic number:
The atomic number is the total number of protons in the nucleus of an atom.
Mass/Nucleon number:
Mass/Nucleon number refers to the total number of protons and neutrons in the nucleus of an atom.
Subatomic particles:
Electrons, Protons and neutrons are called subatomic particles.
Ions
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Ions have unequal number of protons and electrons.
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Ions are formed due to the loss and gain of electron.
Ions can be identified in two respects:
Cations:
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Positively charged ions are called Cations
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Cations are formed due to the loss of electron.
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Cations have more protons than electrons.
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Number of charges on the cations indicates the number of electrons donated.
For example:
Anions:
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Negatively charged ions are called Anions.
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Anions are formed due to gain of electrons.
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Anions have more electrons than protons.
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Number of negative charges on the Anions indicate the number of electrons taken.
For example:
Isotopes
Isotopes are the atoms of the same element that have same number of protons but different number of neutrons.
Isotopes have same:
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number of protons
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atomic radius
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electronic configuration
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Similar chemical properties
On the other hand
Isotopes have different:
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number of neutrons
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nucleon number
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physical properties
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relative isotopic mass
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mass number
Points to remember!
Electronic configuration of an atom is the arrangement of electrons in different energy shells of an atom.
n = number of energy shell.
Maximum number of electrons in an energy shell = 2n2
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The number of electrons present in the outermost shell of an atom represents the group number.
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The number of energy shells of an atom represents the period number.
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Metallic elements (group 1,2,3) donate electrons.
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Non-metallic elements (4,5,6,7) gain electrons.
