Summary
Atoms are the basic units of elements, consisting of protons, neutrons, and electrons. Protons and neutrons are found in the nucleus, while electrons orbit outside. Atoms can become ions by losing or gaining electrons, affecting their charge.
- Atom — the basic unit of an element. Example: Atoms are made up of protons, neutrons, and electrons.
- Proton — a positively charged particle in the nucleus. Example: Protons have roughly the same mass as neutrons.
- Neutron — an uncharged particle in the nucleus. Example: Neutrons contribute to the mass number of an atom.
- Electron — a negatively charged particle outside the nucleus. Example: Electrons have about 1/1800 the mass of a proton.
- Ion — an atom or group of atoms with a net charge due to loss or gain of electrons. Example: Losing electrons creates positive ions, while gaining electrons creates negative ions.
- Proton Number (Z) — the number of protons in an atom. Example: The proton number determines the element's identity.
- Mass Number (A) — the total number of protons and neutrons in the nucleus. Example: The mass number is used to identify isotopes.
- Nuclide — a specific type of atom or nucleus with a particular proton and mass number. Example: Nuclides are represented with symbols like ¹²C for carbon.
Exam Tips
Key Definitions to Remember
- Atom: the basic unit of an element.
- Proton: a positively charged particle in the nucleus.
- Neutron: an uncharged particle in the nucleus.
- Electron: a negatively charged particle outside the nucleus.
- Ion: an atom or group of atoms with a net charge.
Common Confusions
- Confusing the mass number with the proton number.
- Misunderstanding the difference between atoms and ions.
Typical Exam Questions
- What is the charge of a proton? Positive
- How does an atom become a positive ion? By losing electrons
- What particles are found in the nucleus? Protons and neutrons
What Examiners Usually Test
- Understanding of atomic structure and the role of protons, neutrons, and electrons.
- Ability to differentiate between atoms and ions.
- Knowledge of how to calculate the mass number and identify nuclides.