Chapter 4- The Atom Flashcards
Define an atom
An atom is the smallest building block of matter.
Define atomic mass unit (a.m.u)
One-twelfth of the mass of a carbon-12 atom.
Define an isotope
An atom with the same number of protons but a different number of neutrons in its nucleus.
Define relative atomic mass
The mass of the element compared with the mass of a carbon-12 atom.
Define electron configuration
The arrangement of electrons in an atom.
Define Pauli’s exclusion principle
Electrons of opposite spin occupy the same orbital.
Define the Hund’s rule
Electrons enter orbitals singly before pairing up.
Define valence electrons
The electrons in the outermost energy level of the atom that will determine how an atom will react in a chemical reaction.
Define the term core electrons
The remaining electrons that make up the atom.
What are the 3 fundamental particles in atoms?
- Protons
- Neutrons
- Electrons
Which of the particles contribute to mass and volume of an atom?
Protons and neutrons contribute to the mass of an atom and electrons contribute to the volume of an atom.
What is holding the particles in the nucleons?
Strong nuclear forces are holding the particles together and they are so strong they overcome repulsive forces the protons have on each other.
When does an atom bomb occur?
An atom bomb occurs when a nucleus is split because a lot of energy was released.
TRUE OR FALSE
Chemical reactions influence both the nucleus and electrons.
False: chemical reactions only influence the electrons, not the nucleus.
Describe the atomic number (z)
- The number of protons in an atom
- Elements are arranged on the table in order of atomic numbers.
- Element’s unique characteristics/properties are due to the amount of protons the element contains
- It is usually the small number.
Describe the atomic mass number (A)
- Tells us how many neutrons there are in the nucleus.
- Number of neutrons= Atomic mass number- number of protons.
What is nuclear notation?
When the mass number and atomic number change position in the nuclear notation.
Which energy levels are further away from the nucleus?
The higher energy levels.
How do the electrons move in the energy levels?
Electrons can move to higher energy levels by absorbing energy. They can drop to lower energy levels by releasing energy.
How do electrons move so fast?
The energy the electrons have determine the speed of their movement.
In what order to the electrons fill the orbitals.
Electrons always fill the lowest energy level first before filling the next higher energy level.
Explain the energy shells from lowest to highest.
1st electron shell(lowest energy level)- closest to the nucleus; contains max of 2 electrons. ( lowest amount of energy).
2nd energy level- contains max of 8 electrons.
3rd energy level- contains max of 18 electrons.
4th energy level- contains max of 32 electrons, these electrons contain the most energy.
What does the electron configuration describe?
Describes the amount of electrons the atoms contains in each of its orbitals
Why do noble gasses not have any valence electrons?
Because they do not react with other atoms.
