Unit 2: Atomic Structure 1 & 2 Flashcards
What is the maximum number of electrons in an orbital?
An orbital can accommodate a maximum of two electrons with opposite spins.
What does the (n+l) rule indicate about orbital energy?
Lower (n+l) values indicate lower energy orbitals, which are filled first.
Why is understanding electron configuration important?
It helps determine the number of electrons in an orbital and identify sub-shells and principal energy levels.
How do you determine which orbital fills first when (n+l) values are the same?
The orbital with the lower n value has lower energy and fills first.
How many p, d, and f orbitals are there?
There are three p orbitals, five d orbitals, and seven f orbitals.
What are quantum numbers used for in atomic structure?
They describe the characteristics of orbitals, including shape, size, and orientation.
What defines the number of protons in an atom?
The number of protons identifies the element and determines its atomic number.
What is electronic configuration?
The distribution of electrons into different levels, subshells, and orbitals of an atom.
What are the (n+l) values for the 4s and 3d orbitals?
4s: 4, 3d: 5; thus 4s has lower energy than 3d.
When does electron pairing begin in orbitals?
Pairing starts with the 4th electron in p, 6th in d, and 8th in f orbitals.
What defines an atom?
An atom is the smallest unit of an element, composed of a nucleus and electrons.
What is an isotope?
Atoms with the same number of protons but different neutrons and mass numbers.
What does the principal quantum number (n) indicate?
It determines the average distance of an electron from the nucleus.
What are the three main principles of electronic configuration?
Aufbau’s Principle, Pauli’s Exclusion Principle, and Hund’s Rule.
What does Pauli’s Exclusion Principle state?
No two electrons can have the same four quantum numbers; they can share three but differ in spin.
What is the purpose of quantum numbers in relation to electrons?
They describe the position of an electron in an atom, serving as its ‘address.’
What particles make up the atomic nucleus?
The atomic nucleus is made up of protons and neutrons
What are the quantum numbers associated with K-shell electrons?
K-shell electrons have n=1, l=0, m=0, and s=+1/2 or -1/2.
What distinguishes isobars from isotopes?
Isobars have different atomic numbers but the same mass number.
How many orbitals are in an s subshell?
There is 1 orbital in an s subshell.
How is the maximum number of electrons in a shell calculated?
The maximum is calculated using the formula 2n².
List the electronic configuration for Calcium.
Calcium: 1s² 2s² 2p⁶ 3s²
What is the charge and location of electrons?
Electrons are negatively charged particles located in shells around the nucleus.
What are the possible values of the spin quantum number (s)?
+1/2 (clockwise) and -1/2 (anticlockwise)
What does the azimuthal quantum number (l) represent?
It determines the subshell and the shape of the electron cloud.
What does the Principal Quantum Number (n) represent?
It represents the main energy level of an electron in an atom.
Can you give an example of isotopes?
Chlorine-35 (17 protons, 18 neutrons) and Chlorine-37 (17 protons, 20 neutrons).
What is the maximum number of electrons in a p subshell?
The maximum number of electrons in a p subshell is 6.
How is the atomic number determined?
The atomic number is determined by the number of protons in an atom’s nucleus.
What is the range of possible values for the azimuthal quantum number (l)?
It can range from 0 to n - 1.
What quantum numbers characterize the K shell?
n=1, l=0 (1s), m=0, s=+1/2, -1/2, with 2 electrons.
What do isotones have in common?
Isotones have the same number of neutrons but differ in protons and elements.
What does Aufbau’s Principle state?
Orbitals are filled in order of increasing energy in the ground state of atoms.
How are the values of the Azimuthal Quantum Number (l) determined?
Values depend on n; for n=1, l=0; n=2, l=0,1; n=3, l=0,1,2.
How many protons does sulfur have?
Sulfur has 16 protons in its nucleus.
What are the components of a quantum number set?
Principal (n), Azimuthal (l), Magnetic (m), and Spin (s).
What is the electron limit for the M shell?
The M shell can hold a total of 18 electrons.
What are the subshell designations for Azimuthal Quantum Number (l)?
l=0 is s, l=1 is p, l=2 is d, l=3 is f.
How does the Magnetic Quantum Number (m) determine orbital orientation?
m values depend on l; for l=0, m=0; for l=1, m=-1,0,+1.
Can you summarize the K, L, and M energy levels?
K has 1 subshell (1s); L has 2 subshells (2s, 2p); M has 3 subshells (3s, 3p, 3d).
What defines atomic mass?
Atomic mass is how many times an atom weighs compared to one atom of carbon, taken as 12.
What is the definition of an atom?
An atom is the smallest particle of an element that may or may not exist independently.
What is the atomic mass unit (amu)?
AMU is 1/12 of the mass of the carbon-12 isotope, representing the quantity of matter.
How do atoms differ in terms of independent existence?
Some atoms like hydrogen cannot exist independently, while others like helium can.
How is gram atomic mass calculated?
Gram atomic mass is the atomic mass expressed in grams, e.g., sodium’s atomic mass is 23 amu or 23 g.
What is an element?
A pure substance that cannot be broken down further by ordinary chemical means.
What is a molecule and its independent existence?
A molecule is the smallest particle of a compound that can exist independently.
How many known elements are there?
There are a total of 114 known elements.
What distinguishes homoatomic from heteroatomic molecules?
Homoatomic molecules consist of the same element’s atoms, while heteroatomic molecules consist of different elements’ atoms.
What distinguishes compounds from mixtures?
Compounds contain constituents in fixed ratios, while mixtures can have varying ratios.
What is a compound?
A compound is a substance formed from two or more elements that are chemically bonded together.
What is molecular mass?
Molecular mass measures how many times a molecule is heavier than 1/12 of a carbon-12 atom’s mass.
What are ions and their types?
Ions are charged species formed when atoms gain or lose electrons; cations are positive, anions are negative.
What are the rules for forming chemical symbols?
Symbols can have one capital letter or two letters with one uppercase and one lowercase.
What information does a chemical formula contain?
It contains the elements present in the compound and the relative number of atoms of each element.
What corresponds to Avogadro’s number?
Avogadro’s number (6.022 × 10²³) is the number of particles in one mole with a mass of 1 gram atomic or molecular mass.
What is the mole concept’s significance in chemistry?
It calculates the mass of atoms/molecules and determines the number of moles in a given mass.
Give examples of a compound.
Examples include water (H₂O) and copper (II) sulfate (CuSO₄).
Why is following naming rules important in chemistry?
Naming rules provide clarity, preventing confusion between elements and compounds with similar symbols.
What is the definition of matter?
Matter is anything that occupies space and has mass, perceived through senses.
How is molarity defined?
Molarity is defined as the number of moles of solute per liter of solution.
What distinguishes elements from compounds?
Elements are the simplest substances, while compounds consist of two or more elements combined.
What is the difference between molarity and molality?
Molarity depends on temperature; molality is independent of temperature.
How many accepted elements are there currently?
There are 118 accepted elements in total.
How can compounds be broken down?
Compounds can only be broken down through chemical reactions, not by physical means.
What is the primary distinction between compounds and mixtures?
Compounds have fixed proportions; mixtures retain individual properties and can vary in ratios.
Give an example of a chemical formula and its compound.
H₂O represents water, consisting of two hydrogen atoms and one oxygen atom.
What does the mole fraction represent?
Mole fraction is the ratio of moles of one component to total moles in the solution.
Why is distilled water considered a compound?
Distilled water consists only of H₂O molecules, free from impurities.
Can you give an example of a molality calculation?
Calculate molality with 36 g glucose in 250 g water: moles of glucose per kg of water.
