1. Isotopes vs. Ions

2. The number of protons (atomic number) determine the identity of an element.

3. Atoms have no overall electrical charge so, an atom must have as many
electrons
as there are
protons
in its nucleus.

4. The atomic number of an element also equals the number of electrons
in a neutral atom of that element.

5. Atoms of the same element with different numbers of neutrons
#1. What is an isotope?
Atoms of the same element with different numbers of neutrons

6. #2. Write what the symbols A, X, and Z stand for in the isotope symbol

7. Isotope Symbol
X: element symbol

8. Isotope Symbol
A: Mass Number
#protons + # neutrons

9. Isotope Symbol
Z: Atomic number
#protons

10. Other ways to write elements:36
17Cl Cl-36
Mass Number
Mass Number
Atomic Number

11. Isotopes of an element have different mass numbers because they have
different numbers of neutrons,
but they have
the same atomic number.

13. Example: Isotopes of Carbon and Hydrogen
protium deuterium tritium
H H H
Isotopes of Hydrogen
Isotopes of Carbon

14. Atomic Mass is the weighted average mass
of all the naturally occurring
isotopes
of that element.

15. #3. Write the symbol for the atom that has an atomic number of 9 and a mass number of 19. How many electrons and how many neutrons does this neutral atom have?
Symbol (must write both symbols):
# Electrons:
# Neutrons:

16. #4 19 (like every atom of Potassium)
How many protons are in the isotope 39K? (Potassium-39)
19 (like every atom of Potassium)

17. #5 Number of Neutrons = A-Z
How many neutrons are in the isotope of 26Mg?
Number of Neutrons = A-Z

18. #6
How many neutrons are in the isotope 43Sc?
22 neutrons

19. #7
How many electrons are in the isotope 23Na? (you can assume the atom is neutral)
11 electrons

20. When some types of compounds are formed atoms may gain or lose electrons

21. ION: an atom that has gained or lost one or more electrons
When some types of compounds are formed atoms may gain or lose electrons
ION: an atom that has gained or lost one or more electrons
**atoms with the same atomic number (number of protons), but different number of electrons

22. CATION
An atom that has lost one or more electrons (has an overall positive charge)
Naming Rule:
element ion

23. CATION
Hydrogen and most metals form cations.

24. A Sodium atom losing an electronNa 19 11
11 Protons
8 Neutrons

25. A Sodium atom losing an electronNa 19 11
11 Protons
8 Neutrons

26. A Sodium atom losing an electronNa 19 11
11 Protons
8 Neutrons

27. A Sodium atom losing an electron+1 Na 19 11
11 Protons
8 Neutrons +1 Na

28. A Sodium atom losing an electron+1 Na 19 11
11 Protons
8 Neutrons +1 Na
Sodium Ion

29. Quick Check!
If a neutral Magnesium atom loses two electrons, what will its overall charge be? -2 +1 +2 -1 C

30. Quick Check!
How many electrons are in an ion of K+1? 39 18 19 20 B

31. ANION Naming Rule: root + “ide” ion
An atom that has gained one or more electrons (has an overall negative charge).
Naming Rule:
root + “ide” ion

32. ANION
Non-metals and occasionally hydrogen form anions.

33. An atom gaining an electronF 17 9
9 Protons
8 Neutrons

34. An atom gaining an electronF 17 9
9 Protons
8 Neutrons

35. An atom gaining an electronF 17 9
9 Protons
8 Neutrons

36. An atom gaining an electronF 17 9
9 Protons
8 Neutrons

37. An atom gaining an electronF 17 9 -1
9 Protons
8 Neutrons F -1

38. An atom gaining an electronF 17 9 -1
9 Protons
8 Neutrons F -1
Fluoride Ion

39. Quick Check!
If a neutral oxygen atom gains two electrons, what will its overall charge be? -2 +1 +2 -1 A

40. Quick Check!
How many electrons are in an ion of Br -1? 35 34 36 79 C

41. Independent Practice