Ch. 12 Test Flashcards
Who discovered the electron?
Thomson
Dalton’s theory
- everything is made of atoms
- atoms are indivisible
- atoms cannot be destroyed
- ex: billiard ball
Thomson’s theory
- chocolate chip cookie
- atoms are a positively charged substance with negatively charged particles scattered about
Rutherford’s theory
- cherry with a pit
- atoms are mostly empty space with a dense, positively charged nucleus
Bohr’s theory
- solar system
- electrons move in definite orbits around the nucleus
Current theory
- cotton
- electrons don’t move in orbits but at high speeds and form an electron cloud
Atomic number
- the ID of the element
- tells you how many protons are in the element
Mass number
- the total amount of protons and neutrons in the element
- find the number of neutrons in the atoms most common isotope by rounding the mass number and subtracting the protons’ amounts
Atomic mass
The weighted average mass of all isotopes of the element
Isotope
Atoms of the same element with different numbers of neutrons; like different ‘flavors’ of an element
The majority of the mass of an atom comes from which subatomic particle(s)
Neutrons + Protons
Which subatomic particles move around the nucleus?
Electrons
Which subatomic particle has no charge and is located in the nucleus?
Neutron
What are the columns on the periodic table called
Groups
What are the rows on the periodic table called
Periods
