Electric Configuration

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Continuous Spectra

White light passed through a prism is broken up in to an array of colours. This array is known as a continuous spectrum.

Emission Spectra

The emission spectra of an element is the spectrum that is observed when light is emitted from an element.

Hydrogen spectrum

Niels Bohr conducted an experiment in which he passed hydrogen light through a prism. Instead of a continuous spectrum he saw a series of narrow  lines

Absorption Spectra

The absorption spectra of an element is the spectrum that is observed after light has passed through the element

Flame tests

Different elements emit different colours, so flame tests can be used to identify the metal cation in a substance.

The Bohr theory 1

Bohr related the emission spectrum of hydrogen to the structure of a hydrogen atom, 1. Electrons orbit around the nucleus in fixed paths called orbits.

Bohr theory 2

The electrons in these orbits (paths) have a fixed amount of energy. Orbits are therefore called energy levels. The energy of the electron is fixed to a definite value or quantised. These energy level can only hold a definite number of electrons

Bohr theory 3

  3. As long as an electron is in any one particular energy level, it neither gains nor loses energy.

Bohr theory 4

4. When an atom absorbs energy, electrons jump from a lower energy level to a higher energy level. Electrons are less stable in the higher energy levels and do not remain there for long.

Bohr theory 5

5. Energy is lost when an electron falls from a higher energy level to a lower energy level. Since an electron can only fall back to certain energy levels, only fixed amounts of light energy can be given off.

Energy Level (n)

An energy level (n) Shell which electrons of equal energy can occupy, An energy level is defined as the fixed energy value that an electron may have.

Energy levels (ground state)

The ground state of an atom is one in which the electrons occupy the lowest available energy levels

Energy levels (electron jump)

When an atom in its ground state is provided with energy, a specific amount of this energy is absorbed and the electrons jump from lower energy levels to higher energy levels. This is called the excited state.

Energy levels (excited state)

The excited state of an electron is one in which the electrons occupy higher energy levels than those available at ground state.

The energy absorbed is…

Equal to the difference in energy between ground state and excited state.

Electrons in the excited state..

Are unstable and fall back down to lower energy levels after a short period of time.

Excess energy is…

released as a photon of light. Light of a definite frequency is given off.

The frequency of light emitted…

Depends on the difference in energy of the two energy levels.

Energy level formula

E2-E1=hf- Energy of higher energy level - Energy of lower energy level is equal to Planck’s constant times frequency of light emitted.

Balmer line series

Contains all the lines in the visible region of hydrogen spectrum.

Lyman line series

Contains all the lines in the ultra violet region of the hydrogen spectrum.

Energy Sublevels

When lines of the spectra were magnified a smaller number of finer lines were revealed. This suggests that the main energy level is made up of a number of levels of different energy known as sublevels and are denoted by the letters s, p, d and f.

Lithium Flame

Crimson

Potassium

Lilac

Sodium

Yellow

Barium

Yellow-green

Strontium

Red

Copper

Blue-Green