Parts of the atom
Which particles are found in the nucleus?
Protons and neutrons
How many protons does an atom with atomic number 21 have?
21 protons
What are isotopes?
Atoms of the same element with different numbers of neutrons
What are valence electrons?
Answer: Electrons in the outermost energy level
Who created the periodic table?
Answer: Dmitri Mendeleev
what charge does a electron have?
negative
How do you find mass number?
Add protons and neutrons
Do isotopes have the same number of protons?
yes
What does the period number tell you?
Answer: The number of energy levels
Who discovered the nucleus?
Answer: Ernest Rutherford
Why are atoms neutral overall?
Because the number of protons equals the number of electrons
An atom has 17 protons and 18 neutrons. What is its mass number?
35
Why are hydrogen-1 and hydrogen-3 considered isotopes?
They have the same number of protons but different numbers of neutrons
How many energy levels does potassium have?
4
What experiment helped Rutherford discover the nucleus?
Answer: The gold foil experiment
Where are electrons located in an atom?
Around the nucleus in energy levels
What does the atomic number tell you?
The number of protons
What makes isotopes different from each other?
Their number of neutrons
How many valence electrons does nitrogen have?
5
What scientist organized elements by patterns and properties?
Answer: Dmitri Mendeleev
Which particle has no charge?
Neutron
How can you calculate neutrons?
Mass number − atomic number
Do isotopes belong to different elements?
No, they are the same element
How many valence electrons does neon have?
8
What did Rutherford’s experiment prove about atoms?
Answer: Atoms have a small dense nucleus