Neutrons Protons Electrons
Structure of the Atom: 1) The nucleus: 2) Electron cloud: There are two regions: 1) The nucleus: With protons and neutrons Positive charge Almost all the atom’s mass 2) Electron cloud: The region where the electron can be found (negative charge) Most of the volume of an atom with almost no mass (empty space).
Atomic Number (Z): Example: Mg (Z=12) → ___ protons (+) and ___ electrons (-) Represents the number of protons in an atom. In any atom the number of protons in its nucleus is equal to the number of electrons around the nucleus. 12 12
Mass Number (A): Chlorine- 34 → 17 p + ___ n Chlorine -35 → ___ p + 18 n Is the sum of the number of protons and neutrons in the nucleus. Example : Magnesium-24 17 17
Atomic # Mass # Protons Electrons Neutrons 4 5 4 5
Atomic # Mass # Protons Electrons Neutrons 4 4 5 4 4 5
Atomic # Mass # Protons Electrons Neutrons 4 4 4 5 4 4 4 5
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 4 9 4 4 5
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 6 4 9 4 4 5 6 6
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 6 6 4 9 4 4 5 6 6 6
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 6 6 6 4 9 4 4 5 6 6 6 6
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 4 9 4 4 5 6 12 6 6 6
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 4 9 4 4 5 6 12 6 6 6 17 35
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 17
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 17 17
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 17 17 18
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 17 17 18 20 22
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 17 17 18 20 20 22
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 17 17 18 20 42 20 22
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 17 17 18 20 42 20 20 22
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 17 17 18 20 42 20 20 22
Atomic # Mass # Protons Electrons Neutrons 4 9 4 4 5 6 12 6 6 6 17 35 17 17 18 20 42 20 20 22
Name Protons Neutrons Electrons Neon - 20 Neon - 21 Neon - 22 10 10 10 11 12 : Atoms with the same # of protons (or Atomic Number, Z), but different # of neutrons (or Mass Number, A). Isotopes
X Symbol (Isotope): Mass number Atomic number Contains the symbol of the element, the mass number and the atomic number: THIS IS NOT THE SAME AS WHAT IS IN THE PERIODIC TABLE! Mass number X Atomic number
F Br Practice: 19 9 80 35 9 35 10 45 9 35 9 35 19 80 1) Find the number of protons number of neutrons number of electrons Atomic number Mass Number 9 35 10 45 9 35 9 35 19 80
2) If an element has an atomic number of 34 and a mass number of 78 what is the number of protons number of neutrons number of electrons Complete symbol 34 44 34 Se 78 34
Naming Isotopes: Just write the name of the element followed by its mass number. Example: Carbon - 12 Carbon - 14 Uranium - 235
Subatomic particles in ions: When atoms gain electrons they become to negative ions (anions): Neutral atom: Cl 0 (17 p+ + 17 e- ) Ion: Cl 1- (17 p+ + 18 e - )
Subatomic particles in ions: When atoms lose electrons they become to positive ions (cations): Neutral atom: Na 0 (11 p+ + 11 e - ) Ion: Na 1+ (11 p+ + 10 e - )
Li Li 6 3 6 3 A neutral atom of lithium has 3 protons and 3 electrons When lithium reacts, it typically looses one electron; giving it 3 protons and 2 electrons Lithium ION: 3 protons (3 +) and 2 electrons (2-) Now it has a NET charge of (1+) 1 + Li 3 6
No charge here: NEUTRAL ATOM (same number of protons as electrons) Li 3 6 No charge here: NEUTRAL ATOM (same number of protons as electrons) 1 + Li 3 6 Charge here: ION Positive charge = more protons than electrons. Negative charge = more electrons than protons.
Na S Al 11 23 + 11 protons; 10 electrons; 12 neutrons. 16 32 2- 13 27 3+ 13 protons; 10 electrons; 14 neutrons.
How Many Protons, Neutrons, and Electrons? Prot. Neut. Elect. N 7 14 3- 7 7 10 Ca 20 41 2+ 20 21 18 Cl 17 33 1- 17 16 18