Chapter 3: Atomic structure
The structure of atoms
1. Use the words in the box to complete the gaps below. Use each word only once.
Missing words: atom, charge, compound, electrons, element, mass, molecules, nucleus, neutrons,
orbit, positive, relative
Atoms are the smallest particle it is still possible to recognise as an_______. Atoms are made
of three types of particle: protons, neutrons and ________. Protons have a relatively
___________ charge and have a relative ______ of 1. Protons are located in the _________
of an atom. Also in the nucleus are the _______. Neutrons have a relative mass of 1 just like
protons but they do not have any ________. Around the nucleus are the electrons which
_____ the nucleus in shells or orbitals. The electrons have a _________ charge of -1 and
have a relative mass of 1/1832. Atoms can join to form ____________. Molecules can be
made of the same _________ or of different atoms. If the molecule is made of different
atoms it is said to be a ____________.
Atomic number and mass number
2. Use your knowledge of atomic number and mass number to complete the table below.
Element
Carbon
Aluminium
Argon
Potassium
Atomic number
Number of
neutrons
6
14
19
Number of
electrons
6
13
18
Mass number
12
27
40
39
Isotopes
3. In the space below write a definition of the term isotope.
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
Relative atomic mass
4. A new element is discovered that is found as two different isotopes. 6XX accounts for 14%
of the new elements isotopes found. The other isotope is 7XX which occurs 86% of the
time. Using this information calculate the relative atomic mass of new element in the
space below. Show your working.
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