Chemistry Topic
Atomic Structure and Ions
- Read notes
- Flashcards
- Quiz
- Confident
Study focus - 3 things
- Atoms contain protons, neutrons, and electrons
- Protons are positive, electrons are negative, and neutrons are neutral
- Ions form when atoms lose or gain electrons, not protons
Section 1Parts of an atom
An atom has a tiny nucleus in the centre with protons and neutrons. Electrons move around the nucleus in shells. Watch out: most of the atom is empty space, even though diagrams make it look packed.
Section 2Charges
Protons have a positive charge. Electrons have a negative charge. Neutrons have no charge, so they are neutral.
Section 3Atomic number and mass number
The atomic number tells you the number of protons. In a neutral atom, it also equals the number of electrons. Mass number is protons plus neutrons.
Section 4Ions
An ion is a charged particle formed when an atom gains or loses electrons. Losing electrons makes a positive ion. Gaining electrons makes a negative ion. This is one of the most common exam slip-ups.
Examples
A neutral atom has 11 protons. How many electrons does it have?
It has 11 electrons. In a neutral atom, protons and electrons are equal, so the charges balance.
A sodium atom loses one electron. What kind of ion forms?
It forms a positive ion. Losing a negative electron leaves the atom with more positive charge than negative charge.
Now let's water it
Session runs notes to flashcards to quiz back-to-back.