Classification of matter

This article provides answers to the following questions, among others:

  • How can substances be classified?
  • What is the difference between a pure substance and a mixture?
  • What is meant by an element?
  • What are chemical compounds?
  • What is the difference between a suspension and an emulsion?
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Structure of matter

This article provides answers to the following questions, among others:

  • How is a substance constructed at the atomic level?
  • What is a molecule?
  • What is meant by a particle?
  • What does an atomic nucleus consist of?
  • Why do not the protons in the nucleus repel each other, causing the nucleus to fall apart?
  • What is an electron shell?
  • What distinguishes a chemical element at the atomic level?
  • What are isotopes?
  • What is an ion?
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Periodic table

This article provides answers to the following questions, among others:

  • How are the elements arranged in the periodic table?
  • What are the periods in the periodic table?
  • Why does the size of atoms increase from top to bottom but decrease from left to right?
  • Which atomic orbitals are occupied by electrons for each element?
  • In which subgroups are the main group elements divided?
  • What are transition metals?
  • What is meant by a metalloid?
  • Which elements are metalloids?
  • How many know elements are metals?
  • What is the meaning of the main group number?
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Rutherford’s atomic model

This article provides answers to the following questions, among others:

  • What is the setting of the gold foil experiment?
  • What are α-particles?
  • What conclusion can be drawn from the gold foil test?
  • How big is the atomic shell compared to the atomic nucleus?
  • How heavy is a proton or a neutron compared to an electron?
  • What percentage of the total mass of an atom is at the core?
  • What are the strengths and weaknesses of Rutherford’s atomic model?
  • What is meant by the term model?
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Bohr’s atomic model

This article provides answers to the following questions, among others:

  • What is meant by a shell?
  • What is a postulate?
  • What distinguishes the ground state of an atom?
  • How can an atom absorb or emit energy?
  • How much energy does it take to stimulate an atom?
  • What happens to the “excess” of energy when an excited atom returns to its ground state?
  • What is a quantum leap?
  • How many electrons have maximum space on a particular shell?
  • What is meant by a valence electron or a valence shell?
  • To what question can Bohr’s model give no answer?
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Bohr-Sommerfeld model

This article provides answers to the following questions, among others:

  • What main innovation did Sommerfeld introduce?
  • How many sub shells does a main shell have?
  • How many electrons have space within a particular subshell?
  • What is meant by the electron configuration of an element?
  • How do you apply the Aufbau prinziple?
  • What statement makes the Pauli exclusion principle?
  • How is the different electron configuration reflected in the periodic table?
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Octet rule

This article provides answers to the following questions, among others:

  • Why do atoms enter into chemical bonds with other atoms?
  • What distinguishes the noble gas configuration?
  • What is meant by the octet rule?
  • In which different ways can atoms reach the noble gas configuration?
  • Why must not the noble gas configuration be equated with a fully occupied shell in Bohr’s atomic model?
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Covalent bonding

This article provides answers to the following questions, among others:

  • How is the noble gas configuration achieved in a covalent bond?
  • Between which types of elements does the covalent bond mainly occur?
  • For which materials does the covalent bond have special meaning?
  • How are covalent bonds represented by the Lewis dot structure?
  • What information is obtained from a molecular formula?
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Ionic bonding

This article provides answers to the following questions, among others:

  • How is the noble gas configuration achieved by an ionic bonding?
  • Between which types of elements does ionic bonding occur mainly?
  • For which materials does the ionic bond have special significance?
  • What is generally meant by the term salt?
  • Which property of an element is characterized by the electronegativity?
  • Which characteristic is shown in the periodic table regarding the electronegativity?
  • How can one infer the ionic bonding character of two elements?
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Metallic bonding

This article provides answers to the following questions, among others:

  • How is the noble gas configuration achieved in a metal bond?
  • For which materials does the metallic bond have special significance?
  • Where does the term “electron gas” come from?
  • Why is it possible to deform metal relatively well compared to ceramics?
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