Atomic Structure 1 Flashcards
Revision (37 cards)
What are atoms?
Atoms make up all substances and are the smallest part of an element that can exist.
What do chemical symbols represent?
Chemical symbols represent an atom of an element, e.g., Na represents an atom of sodium.
How are compounds formed?
Compounds are formed from elements by chemical reactions, which involve the formation of one or more new substances and often an energy change.
What do compounds contain?
Compounds contain two or more elements chemically combined in fixed proportions.
How can compounds be represented?
Compounds can be represented by formulae using the symbols of the atoms from which they were formed, e.g., HCl.
How can compounds be separated?
Compounds can only be separated into elements by chemical reactions.
What is a mixture?
A mixture consists of two or more elements or compounds not chemically combined together.
What happens to the chemical properties of substances in a mixture?
The chemical properties of each substance in the mixture are unchanged.
How can mixtures be separated?
Mixtures can be separated by: * filtration * crystallisation * simple distillation * fractional distillation * chromatography.
What are the processes used to separate mixtures?
The processes used to separate mixtures are physical and do not involve chemical reactions.
What was the first thought about the structure of atoms?
Initially, atoms were thought to be tiny spheres that could not be divided.
What does the plum pudding model describe?
The plum pudding model describes the atom as a ball of positive charge with negative electrons embedded in it.
What did the alpha particle scattering experiment conclude?
The conclusion was that the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged.
What was observed during the alpha particle scattering experiment?
Some alpha particles emerged from the foil at different angles, and some even came straight back.
What does the scattering experiment demonstrate about alpha particles?
Positively charged alpha particles were being repelled and deflected by a small concentration of positive charge in the atom (nucleus).
What did Neil Bohr suggest about electrons?
Neil Bohr suggested that electrons orbit the nucleus at specific distances.
What did later experiments reveal about the nucleus?
Later experiments revealed that the positive charge of any nucleus could be subdivided into smaller particles, each having the same amount of positive charge (protons).
What did James Chadwick’s work provide evidence for?
James Chadwick’s work provided evidence for the existence of neutrons within the nucleus.
What is the atomic number?
The atomic number is the number of protons in an atom of an element.
What is true about all atoms of a particular element?
All atoms of a particular element have the same number of protons.
What is the relative charge of a proton?
+1
What is the relative charge of a neutron?
0
What is the relative charge of an electron?
-1
What is the overall charge of an atom?
An atom has an overall charge of 0, so the number of protons equals the number of electrons.
