SCH4U - Structure and Properties of Matter Flashcards
Electrons
An electron is a negatively charged subatomic particle that can be either bound to an atom or free (not bound). An electron that is bound to an atom is one of the three primary types of particles within the atom
Symbol: e^-1
mass: 9.109 x 10^-31
Protons
A proton is a subatomic particle found in the nucleus of every atom. The particle has a positive electrical charge, equal and opposite to that of the electron.
Symbol: P^1+
mass: 1.673 x 10^-27
Neutrons
A neutron is a subatomic particle found in the nucleus of every atom except that of simple hydrogen. The particle derives its name from the fact that it has no electrical charge; it is neutral. Neutrons are extremely dense.
Symbol: n^0
mass: 1.675 x 10^-27
Radioactive
When Atoms have more protons then neutrons so therefore become unstable
Isotopes
Isotopes are atoms that have the same number of protons (same) but different number of neutrons
Nucleus
The nucleus is the positively charged center of an atom and contains most of its mass. It is composed of protons, which have a positive charge, and neutrons, which have no charge.
Atomic Number/What Letter represents Atomic Number
Number of protons a given atom carries / The letter “Z” represents the atomic number
Mass Number/What Letter represents Mass Number
Number of nucleons (Number of protons + Number of Neutrons) in a nucleus
The letter “A” represents the Mass number
Photons
a quantum of electromagnetic radiation/Em radiation is a stream of light energy particles. Each of these particles are known as photon
Orbital
A region around the nucleus where electrons are highly likely going to be found. Their shapes depends on the l value
Quantum Numbers
The set of numbers used to describe the position and energy of the electron in an atom are called quantum numbers.
Principal Quantum number (n)
It describes the shells or energy levels which electrons can exist within an atom. The distance between each level and the nucleus is based on the amount of energy the electrons have./ n = the energy level around the atom, basically each electron shell = 1n, 2n, 3n
***Electrons can’t exist between energy levels(No decimals/fraction values)
Secondary Quantum Number (L)
the shapes of atomic sublevels and their orbitals.,
shapes of atomic sublevels and their orbitals.
For energy level n, the available values of L range from 0 to (n-1). For example,
n = 1, L = 0
n= 2, L = 0, 1
n= 3, L = 0, 1, 2
The values of l are more known by their letter designations.
l Letter Designations
0 s (sharp or spherical)
1 p (principal)
2 d (diffuse)
3 f (fundamental)
4 g
Magnetic Quantum Number (mL)
The orientation of the sublevel shapes in space. The values can range from -L to +L
For example, for L = 2, the ml available are: -2, -1, 0, 1, 2. Each value signifies a different orientation of the sublevel.
The quantum spin number (ms)
The quantum spin number denotes the two possible states of the electron when it is placed in an external magnetic field.
The two possible states are +½ and -½ , where they represent the spin directions of the electron.
Energy levels (shells)
the orbits around the nucleus.
Sublevels (subshells)
the different shapes and energy of electron orbitals can take on in a certain energy level. (s, p, d, f, and g)
Electron Configuration
to show how electrons can arrange themselves within an atom in the ground state (the lowest energy state) which showcases the patterns within the periodic table.
The electron configuration will give the location and the number of electrons that are found in the energy levels of a neutral atom, or an ion.
Aufbau Principle
The Aufbau principle describes that an atom can be seen as being assembled by filling it up with electrons.
It will always fill electrons beginning at the lowest available energy orbitals before filling the next higher energy orbitals.
This, in turn, provides us the sequence of electron configuration:
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s
Pauli-Exclusion Principle
“No two electrons can ever have the same set of quantum numbers.”
This means that two electrons can have the same n, same l, and same ml for as long as the two electrons have different (or opposing) spin numbers.
In other words: “Each orbital (each ml orientation) can house two electrons.”
Hund’s Rule
Hund’s Rule is used when we have partially filled sublevel orbitals. Hund’s rule is stated as follows:
“Every orbital is singly occupied before it is doubly occupied.”
This means that there is a certain sequence which electrons will fill into orbitals within a sublevel.
RadioIsotope
an isotope that spontaneously decays to produce two or more smaller nuclei and radiation
How does Dalton’s model describe atoms?
Small indestructible spheres
stated:
- All matter is made of atoms.
- Atoms of the same element have the same average mass, size and unique properties.
- Atoms cannot be converted into atoms of another element through chemical reactions.
- Atoms of different elements combine in specific proportions to form compounds.
How did Thompson prove that electrons exist and that they are negative?
Experimented with cathode ray tubes which create beams of small particles. He placed charged plates on either side of the beam to determine its charge.
Observed that the beams are deflected towards positively charged plates. The beam must contain negative particles because opposite charges attract.
Since atoms are neutral, they must contain negative particles that can be removed from a positive material.
