This document contains a worksheet on atoms and their complexity with various activities and exercises for students. The activities include explaining the differences between atoms, elements, ions, and isotopes. Students are asked to identify incorrect formulas from Dalton's atomic theory, complete tables with atomic properties, match scientists to their atomic models and experiments, calculate atomic sizes, write electron configurations, and complete a crossword puzzle with atomic terms. The worksheet draws on concepts from atomic structure and theory to help students learn about the composition and behavior of atoms.

1. Physics and Chemistry 3rd ESO Albarregas High School
ATOMS AND THEIR COMPLEXITY
Activities
Usee the periodic table to look for the atomic number of the elements in those activities you need it.
1. Explain the differences between:
(a) An atom and an element.
(b) An atom and an ion.
(c) An element and an isotope.
(d) A cation and an anion.
2. In this picture you have the formulas used by Dalton for several
compounds. Which of them are wrong according to the contemporary
chemists? If you need it, look for information on the internet.
3. Complete the table:
Particle Relative mass Relative charge Is it in the
nucleus?
proton 1
0
1/1840
4. According to present knowledge, these statements of the atomic theory of Dalton are false.
Explain why.
(a) Atoms are uncuttable particles.
(b) All atoms of the same elements are equal.
5. Complete the table with the characteristics of several atoms. Use the periodic table to find
the name or the symbol of the elements.
Element Symbol Z A Protons Neutrons Electrons
10 22
42
20 Ca
Lithium 7
6 8
Helium 3
18 8
6. Match the scientists with their experiments and their models of atom.
“Plum pudding” model J. Dalton
Undivisible particle N. Bohr Cathodic rays
Nuclear model J. J. Thomson Gold foil experiment
Electrons in shells E. Rutherford
Little planetary system
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2. Physics and Chemistry 3rd ESO Albarregas High School
7. If the nucleus of an atom had the size of the head of a pin (diameter = 2 mm), how big
would the atom be? Take into account that the atomic nucleus is one hundred thousands
times smaller than the atom.
8. Iron has four different isotopes whose mass numbers are 54, 56, 57 and 60. How many
protons, neutrons and electrons does each of them have?
9. Write the electron arrangement of these elements of the third period. What do they have in
common?
Element Symbol Z Electron arrangement
Sodium
Aluminium
Phosphorus
Chloride
Argon
10. How many shells do the elements of the fifth period have? And the elements of the
seventh period?
11.Write the electron arrangement of these elements of the thirteenth group. What do they have
11.Write
in common? How many valence electrons do they have?
Element Symbol Z Electron arrangement
Boron
Aluminium
Gallium
Thallium
12. Write the electron arrangement of all noble gasses. What do they have in common?
13. Complete the table with the characteristics of several ions. Use the periodic table to
find the name or the symbol of the elements.
Element Symbol Z A Protons Neutrons Electrons Charge
9 22 -1
42
20 Ca2+
Lithium 7 +1
5 8 -3
Helium 3 2
18 10 -2
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3. Physics and Chemistry 3rd ESO Albarregas High School
14. Crossword:
ACROSS DOWN
1. Positively charged subatomic particle 2. Scientist that discovered the atomic nucleus
5. ____________ number is the number of protons of a 3. Scientist that discovered the electron
nucleus 4. Atoms of an element that have different number of
6. atom whose electrical charge is not balanced neutrons
7. Rutherford used a foil made of this metal in his 8. Very light particle that moves around the nucleus
experiment 12. Letter or pair of letters used to represent an element
9. Subatomic particle that has no charge 13. It is used to represent a compound
10. Danish chemist who stated that electrons are
arranged in shells
11. Heaviest part of an atom
14. British chemist who thought that atoms were
unbreakable particles
15. Chemically inactive gasses
16. ____________ number is the number of particles of
a nucleus
17. Thomson found __________ rays when he was
trying to study electrical conductivity of gasses
Activities from your P&C book
On page 64: Exercise 15
On page 68: Exercise 21, 30, 34 and 35
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