Q 2 1 Name 3 subatomic particles 2

Q 2 1. Name 3 subatomic particles. 2. What particle has no charge? 3. Which atom has the least mass? 4. What is true about all neutral atoms? 5. How can the atomic number of an atom be determined?

Today’s Objective: I understand the development of current atomic theory.



Isotope v Same protons but different neutrons v Same atomic number v Difference of # of neutrons v Isotope # is # of p + n

What would it take for an atom to have an overall neutral charge? Same # of protons as electrons

Atomic Number v The number of protons in the nucleus v All atoms of different elements have a different number of protons

Atomic Mass Number v The number of protons + neutrons v Neutrons = Mass # - Atomic # v Mass # can change and the element stays the same


Chemical Symbols • ONE capital letter followed by lowercase letter(s) if necessary. • Often not the first letter of its name Co vs. CO Metal that forms bright blue solid compounds Poisonous gas

How could the mass contain a decimal if it is the number of protons + neutrons?

Isotope Mass Abundance Li-6 6 7. 5% Li-7 7 92. 5%

Atomic Mass: The weighted AVERAGE of the masses of all isotopes as found in nature Li-6 Li-7

AMU: Atomic Mass Unit How much 1/12 of a Carbon -12 weighs

Calculating Atomic Mass Number:

Boron has 2 common isotopes: B-10 & B-11 In nature, 80% of all Boron is B-11 and 20% is B-10 Mass x abundance B-10: 5 P + 5 N = 10 amu X. 20 = 2 B-11: 5 P + 6 N = 11 amu X. 80 = 8. 8 Add: 2 + 8. 8 = 10. 8

Whiteboard Practice

What is the charge of this atom? Negative -1

Positive +1 What is the charge of this atom?

The atomic mass of an atom is 28. It’s atomic number is 10. How many neutrons does it have? 18 neutrons 28 -10 = 18

What is the difference between Carbon-6 and carbon-7? # of Neutrons

A neutral atom has 15 electrons. How many protons does it have? 15

A neutral atom has 94 electrons. How many protons does it have? 94

All atoms of an element have the same A. B. C. D. Mass number Number of isotopes Atomic number Number of neutrons

What is the charge of this atom? Neutral

A neutral atom has 65 electrons. How many protons does it have? 65
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