Powerpoint 3 Flashcards
What does the atomic number represent?
The number of protons in an atom.
What does the mass number represent?
The total number of protons and neutrons in an atom.
What are isotopes?
Atoms of the same element with the same atomic number but different mass numbers.
What are Rutherford’s conclusions from the gold foil experiment?
Atoms are mostly empty space, and the nucleus is dense and positively charged.
What is Avogadro’s number?
6.022 × 10^23.
What is the mole?
The amount of substance containing 6.022 × 10^23 particles.
Who was J.J. Thomson, and what did he discover?
J.J. Thomson discovered the electron using cathode ray tube experiments.
What evidence did J.J. Thomson use to prove electrons are negatively charged?
Electrons were deflected toward the positive plate and away from the negative plate. He used a cathode ray.
What is the plum pudding model?
J.J. Thomson’s model where electrons are embedded in a positive “pudding” like raisins in a cake.
What did Ernest Rutherford discover?
Rutherford discovered that atoms have a dense, positively charged nucleus through the gold foil experiment.
What were Rutherford’s conclusions from the gold foil experiment?
Atoms are mostly empty space, and the nucleus contains most of the atom’s mass and positive charge.
Who was John Dalton, and what did he contribute?
John Dalton proposed the atomic theory, stating that:
1. Elements are made of tiny particles called atoms.
2. All atoms of a given element are identical.
3. Atoms cannot be created, divided, or destroyed.
4. Atoms combine in whole-number ratios to form compounds.
