Atomic Structure and Subatomic Particles
This section introduces the fundamental concepts of atomic structure, including the definition of atoms, elements, compounds, and mixtures. It also covers the historical development of atomic theory and the properties of subatomic particles.
Definition: An atom is the smallest part of an element that can exist, with a neutral overall charge.
The history of atomic theory is presented chronologically, highlighting key contributors:
- Democritus: Proposed the idea of indivisible particles separated by empty space.
- John Dalton: Introduced the concept of atoms as solid spheres.
- J.J. Thomson: Discovered electrons and proposed the plum pudding model.
- Ernest Rutherford: Conducted the alpha scattering experiment, leading to the nuclear model.
- Niels Bohr: Introduced the concept of electronic shells.
- James Chadwick: Discovered neutrons.
Highlight: The alpha scattering experiment was crucial in establishing the nuclear model of the atom, revealing that atoms are mostly empty space with a small, dense, positively charged nucleus.
The properties of subatomic particles are detailed:
- Protons: Relative charge +1, relative mass 1
- Neutrons: Relative charge 0, relative mass 1
- Electrons: Relative charge -1, relative mass very small
Vocabulary: Isotopes are different forms of the same element with the same number of protons but different numbers of neutrons.
The concept of relative atomic mass is introduced, with the formula provided for its calculation.
