Chapter 3
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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How did Dimitri Mendeleev contribute to the periodic table?
Dimitri Mendeleev first created the periodic table but a few elements were in the wrong places.
How did Henry Mosley contribute to the periodic table?
He organized the periodic table by atomic number.
What atom model do we currently use?
The electron cloud model.
What two particles are found in the nucleus of an atom?
Protons and neutrons
What is an atom?
An atom is the smallest unit of an element that maintains the properties of that element.
What is the nucleus?
The nucleus is the small, dense center of an atom that has a positive electric charge.
How are protons and neutrons related in size and mass?
The size and mass of protons and neutrons are almost identical.
What charge do protons have?
Positive
What charge do neutrons have?
Neutral
What charge do electrons have?
Negative
How are electrons’ size related to the size of protons and neutrons?
Electrons are much smaller than protons and neutrons.
Where are electrons located and how do they move?
Electrons move around the outside of the nucleus in energy levels and orbitals. They are constantly on the move but they do remain in predictable energy levels.
What overall charge do atoms have?
Atoms have an overall neutral charge.
What is the relationship between the number of protons and electrons?
The number of protons in and atom is equal to the number of electrons in the atom.
Will the charge of an atom change if the number of neutrons is changed?
No because neutrons are neutral.
How many electrons can each energy level hold?
energy level 1–2 electrons energy level 2–8 electrons energy level 3–18 electrons energy level 4–32 electrons
What is a quark?
A quark is a smaller particle that makes up protons and neutrons – 6 quarks are known to exist.
What is the atomic mass?
The atomic mass is the total mass of protons, neutrons, and electrons in an atom –mostly composed of protons and neutrons (also called mass number).
What is the atomic number?
The atomic number is the number of protons/electrons in an atom- this identifies the element.
What is the atomic mass measured in?
AMU
How do you find the number of neutrons based on information given in the periodic table?
Rounded mass number – atomic number equals the number of neutrons.
What is an isotope?
An isotope is an atom of the same element that has a different number of neutrons. Different isotopes may have different properties.
Mass-atomic #=
of Neutrons
Atomic #=
Protons/electrons