C1: Atomic Theory Flashcards
What is an element?
Substances made up of only one type of atom. Each group contains elements with similar chemical properties.
What are compounds?
Substances made up of 2 or more elements chemically bonded together.
What is the Law of Conservation of Mass?
The total mass of the products formed in a reaction is equal to the total mass of the reactants. No new atoms are created or destroyed so there should be the same number of either side of a chemical reaction.
What are aqueous solutions?
Substances dissolved in water.
What is a mixture?
Made up of 2 or more substances that are not chemically bonded. Can be separated physically.
What did John Dalton do?
Suggested that substances were made up of solid spheres called atoms. Each element had its own atoms which couldn’t divide or split.
What did JJ Thomson do?
Discovered electrons, tiny negatively charged particles and that atoms have no overall charge. Came up with the Plum Pudding Model which was a ball of positive charge with electrons embedded in it.
What did Ernest Rutherford do?
Discovered nucleus and protons by the alpha particles experiment. He aimed a beam of alpha particles at thin gold foil. Most went straight through, some scattered and some reflected back. Concluded there was a nucleus of positive charge repelling positive alpha particles.
What did Niels Bohr do?
Suggested electrons orbit nucleus in shells at specific distances.
What did James Chadwick do?
Provided evidence to show there were neutrons in the nucleus.
What is the relative atomic mass and atomic number?
Relative Atomic Mass - Protons + Neutrons
Atomic Number - Number of Protons
What are ions?
Charged atoms formed when an atom gains or loses electrons so is either positively or negatively charged.
What are isotopes?
Atoms of the same element with a different number of neutrons.
What is the group number?
The amount of electrons of an element’s atom’s outermost shell.
