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The 2,400-year search for the atom - Theresa Doud

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450 B.C.    Democritus

He introduces the idea of “atomos” as uncuttable particles.

1803         John Dalton - The “Marble Model or Billiard Ball Model”

He re-introduces “atomos” as the term atom; atoms being the smallest particles of matter.

1897         J.J. Thomson - The “Plum Pudding Model”

He discovers the electron while working with cathode rays, sub-atomic particles with a negative charge. He calls the particles “electrons” which are scattered throughout a "sea" of positive charges, like a plum pudding.

1911         Ernest Rutherford (together with his post-grad students Marsden and
Geiger) - The Nuclear Model

He discovers the nucleus and protons at the centres of atoms, which he calls the nucleus. He says that the nucleus is filled with positive protons and electrons randomly orbiting the nucleus.

1913         Niels Bohr - The Planetary Model

He proposes a Planetary Model for the atom, where electrons move around the nucleus in fixed orbits named energy levels (like planets orbit around the sun).

1926         Werner Heisenberg & Erwin Schrödinger - The Quantum mechanical                         model

Heisenberg and Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position, called an orbital. This atomic model is known as the quantum mechanical model of the atom.

Today       -   THE STANDARD MODEL
-   We know the structure of atoms from smashing atoms together in                            the LHC (particle accelerator) at CERN and in other big labs across                          the globe.
-  We know that electrons are always in motion around the nucleus.

-  Electrons are fundamental particles,

i.e. they cannot be broken into any smaller particles

-      Protons and neutrons vibrate within the nucleus.

-      Protons and neutrons are not fundamental particles, i.e. they

are made up of smaller particles

-      Quarks vibrate within the protons and neutrons.

-      Quarks are fundamental particles.

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Discoverers of the electron, proton and neutron:

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Atomic Structure And Electrons - Structure Of An Atom - What Are Atoms - Neutrons Protons Electrons

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Atomic Number & Mass Number | Properties of Matter | Chemistry | FuseSchool

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Average Atomic Mass: amu and Daltons (Chemistry)

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Isotopes = atoms of an element that have the same number of protons, but differing numbers of neutrons in their nuclei.

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Do a calculation using isotopes to determine the relative atomic mass of an element

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Do a calculation using isotopes to determine the relative atomic mass of an element

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Practice Problem: Isotopic Abundance and Atomic Mass

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How to Write Electron Configuration 6 examples + Exceptions Chromium & Copper (Chemistry)

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Rules that electrons obey to build up an atom

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Rules that electrons obey to build up an atom

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Aufbau principal

Pauli’s Exclusion Principle

Hund’s Rule

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1. ORBITAL
2. ENERGY LEVEL DIAGRAM
3. HUND'S RULE
4. THE PAULI EXCLUSION PRINCIPLE

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DEF:

VALENCY = the number of electrons an atom must lose or gain to achieve a filled outermost energy level, to attain its most stable state.

CORE ELECTRONS = the electrons found below the outermost energy level in an atom.

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Chemical Bonding - Ionic vs. Covalent Bonds

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COVALENT BONDING

IONIC BONDING

METALLIC BONDING

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Metals are made up of a "sea" of delocalised electrons surrounding positive kernels (cations).

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Use to calculate Molar Masses

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Types Of Chemical Bonds - What Are Chemical Bonds - Covalent Bonds And Ionic Bonds - What Are Ions

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GCSE Chemistry Revision "Ionic Bonding 1"

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S2.2.1 Describe how the covalent bond is formed via electron sharing [SL IB Chemistry]

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Intramolecular Bond:

is a bond which occurs between atoms within molecules.

Covalent bond:

is a bond which occurs due to sharing of at least one pair of electrons by two nonmetal atoms.

Non-polar covalent (pure covalent):

is an equal sharing of electrons.

Polar covalent:

is an unequal sharing of electrons leading to a dipole forming (as a result of electronegativity difference)

Electronegativity:

is a measure of the tendency of an atom to attract a bonding pair of electrons.

Ionic bond:

is a bond which occurs due to a transfer of electrons and subsequent electrostatic attraction.

Metallic bonding:

is a bond between positive kernels and a sea of delocalised electrons.

Bond Energy:

the amount of energy needed to break a specific bond.

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Due to VSEPR

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FORMATION OF SALTS

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How atoms bond - George Zaidan and Charles Morton

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ACAPELLASCIENCE

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The Molecular Shape of You (Ed Sheeran Parody) | A Capella Science

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Discovery of the Electron: Cathode Ray Tube Experiment

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BLOCKS: s,p,d,f-blocks in periodic table

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BLOCKS: s,p,d,f-blocks in periodic table

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A block of the periodic table is a set of chemical elements having their differentiating electrons predominately in the same type of atomic orbital. ... Each block is named after its characteristic orbital: s-block; p-block; d-block; and f-block