UNIT 2 - The Periodic Table & The Atomic Theory Flashcards
Lesson 01/30/2025
What causes patterns in the periodic table?
Patterns in the periodic table occur as a result of regular changes in the structure of the atoms of elements.
Why do elements line up in columns in the periodic table?
Elements line up in columns because they are similar in the arrangement of their electrons.
What did Niels Bohr suggest about electrons?
Niels Bohr suggested that electrons move around the nucleus of an atom in orbits or shells.
What is a Bohr model?
A Bohr model is a diagram that shows how many electrons are in each shell surrounding the nucleus of an atom.
What are electron shells?
Electron shells are regions surrounding the nucleus of an atom, each at a certain distance from the nucleus.
How many electrons can each shell hold?
Each shell holds a different number of electrons:
1st shell: 2, 2nd shell: 8, 3rd shell: 8, 4th shell: 18.
What is the first step in drawing a Bohr model diagram?
Write the element symbol.
How do you determine the number of electrons in a neutral atom?
Check the periodic table to see how many electrons the element has (in a neutral atom, number of protons = number of electrons).
What do you do after determining the number of electrons?
Pay attention to how many electrons each shell can hold and figure out how many shells the atom has.
How do you represent electrons in a Bohr model diagram?
Use a dot to represent an electron, starting with the innermost shell and placing the correct number of electrons on the diagram.
What are valence electrons?
Valence electrons are the electrons in the outermost shell.
What does the period number indicate?
The period number indicates the number of shells that contain electrons.
What happens when a valence shell is full?
When a valence shell is full, the atom is stable.
Why are noble gas atoms virtually unreactive?
Noble gas atoms (group 17) have filled valence shells, which makes them virtually unreactive.
What do atoms in other groups need to do to become stable?
Atoms in other groups need to gain or lose electrons to become stable (full valence shell) during a chemical reaction.
