Atomic Models: Dalton and Rutherford

Dalton's Atomic Model proposed that all matter is made up of tiny, indivisible particles called atoms. He suggested that atoms of a specific element have the same mass and properties, while atoms of different elements have different masses and properties. Additionally, he stated that atoms combine in fixed whole-number ratios to form compounds. Chemical reactions merely rearrange atoms, not creating or destroying them.

Rutherford's Gold Foil Experiment involved shooting alpha particles (positively charged) at a thin gold sheet. Most particles passed straight through, suggesting that atoms have mostly empty space. However, some particles were deflected at large angles, indicating a dense, positively charged center called the nucleus. This experiment revealed that the atom's mass and positive charge are concentrated in a tiny nucleus, with electrons occupying the vast, empty space around it.

Bohr's Atomic Theory proposed that electrons orbit the nucleus in specific energy levels or shells. Electrons can only exist in these discrete energy levels, not between them. When an electron absorbs energy, it jumps to a higher energy level (excitation). Upon returning to a lower level, it releases energy as light (photon emission), with the light's energy corresponding to the energy difference between the levels. While this model explained the discrete spectra of elements, it was simplified and later replaced with more complex models.

Describes the movement of an electron from a lower energy level to a higher energy level by absorbing energy. This often involves absorbing light or heat, causing the electron to jump to a higher orbital.

Describes the process where an electron, having been excited to a higher energy level, releases energy and falls back to a lower energy level. This energy release often manifests as light emission, creating spectral lines.