Chapter 1: Atomic Structure Flashcards
1
Q
Atoms
A
• An atom has a tiny nucleus at its center, surrounded by electrons
2
Q
Chemical Equations
A
• No new atoms are created or destroyed in chemical reactions; mass of reactants = mass of products
3
Q
Separating Mixtures
A
- a mixture is two or more substances that are not chemically combined together
- they can be separated using physical means, such as filtration, crystallisation, and simple distillation
4
Q
Fractional distillation and paper chromatography
A
- a way of separating miscible liquids using a fractionating column. The separation is possible because of the different boiling points of the liquids in the mixture
- paper chromatography separates mixtures of substances dissolved in a solvent as they move up the paper of paper. The different substances are separated because of their different solubilities in the solvent used.
5
Q
History of the Atom
A
- new evidence has been gathered from experiments of scientist who have used their model of the atom to explain their observation and calculations
- key ideas were proposed successively by Dalton, Thomson, Rutherford, and Bohr, before the arriving at the model of the atom used today.
6
Q
Structure of the atom
A
- atoms contain an equal number of protons and electrons, so carry no overall charge
- atomic number = number of protons (number of electronics)
- mass number = number of protons + neutrons
- atoms of the same elements have the same number of protons (and hence electrons) in their atoms
7
Q
Ions, atoms and isotopes
A
- atoms that gain electrons form negative ions. If atoms lose electrons they form positive ions
- isotopes are atoms of the same element with different number of neutrons. They have identical chemical properties, but their physical properties, such as density can differ.
8
Q
Electronic Structure
A
• the number of electrons in the outer shell determines how the element reacts
