Atomic Structure
What are the three major subatomic particles?
Protons, neutrons, and electrons.
I have an atomic number of 8. Who am I?
Oxygen (O)
Question: Do groups run horizontally or vertically on the periodic table?
Vertically
Electrons have a positive charge.
Electrons have a negative charge.
Match each particle with its charge:
Proton
Neutron
Electron
Proton = +1
Neutron = 0
Electron = −1
I am in Period 3 and Group 1. Who am I?
Sodium (Na)
What family is found in Group 18 (8A)?
Noble gases
Periods run up and down the periodic table.
Periods run horizontally. Groups run vertically.
An atom has 15 protons and a mass number of 31. How many neutrons does it have?
31 − 15 = 16
I am a nonmetal, I'm in Period 3, and I'm a halogen. Who am I?
Chlorine (Cl)
Classify each as a metal, nonmetal, or metalloid:
Na, O, Si
Na = Metal
O = Nonmetal
Si = Metalloid
A student labels ²³₁₁Na as:
11 protons
11 neutrons
11 electrons
What's wrong?
It has 12 neutrons.
23 − 11 = 12.
A neutral atom has 20 protons. How many electrons does it have?
20 electrons
I am a metalloid, I'm in Period 3, and my atomic number is 14. Who am I?
Silicon (Si)
Which pair should have the most similar chemical properties?
A. Na and K
B. Na and Cl
C. Mg and O
D. C and Ne
A. Na and K
They're in the same group.
The atomic number tells you the total number of protons AND neutrons.
Atomic number = number of protons.
Mass number = protons + neutrons.
An atom has:
Give its element, atomic number, and mass number.
Potassium (K)
Atomic # = 19
Mass # = 39
I am in Period 4, I am an alkaline earth metal, and I have 20 protons. Who am I?
Calcium (Ca)
Name all four families:
Group 1 = Alkali metals
Group 2 = Alkaline earth metals
Group 17 = Halogens
Group 18 = Noble gases
A student says:
³⁵₁₇Cl has 17 protons, 18 neutrons, and 35 electrons.
What's wrong and what should it be?
A neutral chlorine atom has 17 electrons.
35 is the mass number.