c1. atomic stucture Flashcards
what are all substances made of?
atoms
what is an atom?
smallest part of an element that can exist
how are atoms represented?
chemical symbols
how many elements are there?
about 100
how are compounds formed?
from elements by a chemical reactions
what is a chemical reaction?
they involve the formation of one or more new substances and often involve a detectable energy change.
what are compounds?
substance that contains two or more elements chemically combined in fixed proportions
How can compounds be separated into elements?
chemical reactions
what is a mixture?
Two or more elements or compounds not chemically combined together the properties of each substance is an unchanged.
how can mixtures be separated?
Filtration crystallisation simple distillation, fractional distillation and chromatography
What model of the atom was developed following the discovery of an electron?
Plum pudding model
Describe the plum pudding model of the atom
Fall of positive charge with negative electrons embedded in it
What was concluded from the alpha particle scattering experiment?
The mass of the atom was concentrated at the centre and the nucleus was charged
What model replaced the plum pudding model?
Nuclear model
How did Niels bohr adapt the nucleus model?
He suggested that electrons orbit the nucleus at specific distances
What did the experimental work of James Chadwick prove?
The existence of neutrons in the nucleus
What is the relative charge of the proton
+1
What is the relative charge of a neutron?
0
What is the relative charge of an electron?
-1
Why do atoms have no overall charge?
The number of electrons is equal to the number of protons in the nucleus
What is an atomic number?
The number of protons in the nucleus
What is the radius of an atom?
0.1nm or 1x10*-3m
What is the radius of a nucleus?
1x10*-14m
What is the mass of protons and neutrons?
1
What is the mass of electrons?
negligible
What are isotopes?
Atoms of the same element with different numbers of neutrons
How many electrons can occupy the first shell of an atom?
2
How many electrons can occupy the second cell of an atom?
8
How many electrons can occupy the third shell of an atom?
8
