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Atomic Notation

Atomic Notation. http://www.chemicool.com/. Atomic Number Z. The atomic number Z of an element is the number of protons found in the nucleus of the atom of this element. Example : The atomic number of lithium is Z = 3. It means that the nucleus of lithium atom contains 3 protons.

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Atomic Notation

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  1. Atomic Notation http://www.chemicool.com/

  2. Atomic Number Z • The atomic number Z of an element is the number of protons found in the nucleus of the atom of this element. • Example : • The atomic number of lithium is Z = 3. It means that the nucleus of lithium atom contains 3 protons.

  3. Atomic Number Z • According to Bohr-Rutherford model of atomic structure, the atom is neutral. Then, if an atom contains Z protons, it should contain Z electrons. • Example : • The atomic number of chlorine is Z = 17. Chlorine atom contains 17 protons and 17 electrons. • Rule : for a neutral atom, Z = number of protons = number of electrons.

  4. Mass Number A • Lets designate by N the numbre of neutrons in the nucleus of an atom. • And by A the total number of protons and neutrons in the nucleus. • This number A is called Mass Number. (See page 247). • By definition: A = Z + N

  5. Examples • The atomic number of sodium is Z = 11. Its mass number A = 23.Determine the number of protons, electrons and neutrons of this atom. Draw this atom. Solution The atomic number Z = 11, then this atom contains 11 protons. The atom is neutral, then the number of electrons = the number of protons = Z = 11. The mass number A = Z + N, then the number of neutrons N = A – Z = 23 -11 =12 neutrons.

  6. Cont’d • Sodium atom contains 11 p+, 11 e- and 12 no. 2 e- on the first shell (K) 8 e- on the second shell (L) 1 e- on the third shell (M)

  7. Notation of the structure of an atome • The proper notation of the structure of an atom uses the chemical symbol X with both the mass number A (upper left) and the atomic number Z (lower left). X A Z

  8. calculate the number of protons, electrons and neutrons of each of the following atoms:

  9. Families of elements • In chemistry, the term chemical family is used to describe a group of related elements, elements can have common characteristics or proporties. • To understand how to classify elements in a family, you work individually the ScienceInquiry Activity, page 216.

  10. Your task • Page 216, Sciences Inquiry Activity : «Patterns of Proporties in a Chemical Family» • Time : 10 to 15 minutes • Answer by writting the questions. • Note : A coinage metal is a metal used to make coins.

  11. Hoomework • Determine the number of protons, electrons and neutrons of each atom. Draw each atom according to Bohr-Rutherford model. What one common charactristic of these atoms do you notice.

  12. Réponses • Hydrogen atom • 1 proton, 1 electron, 0 neutron • Lithium atom • 3 protons, 3 electrons, 4 neutrons • Sodium atom • 11 protons, 11 electrons, 12 neutrons • Potassium atom • 19 protons, 19 electrons, 20 neutrons • Common characteristic : one electron on the outer shell.

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