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Questions and Answers
Which of the following is true about reactive metals such as those in group 1A and 2A?
Which of the following is true about reactive metals such as those in group 1A and 2A?
Which group of elements tends not to lose or gain electrons due to their high ionization energy and slightly positive electron affinity?
Which group of elements tends not to lose or gain electrons due to their high ionization energy and slightly positive electron affinity?
In terms of metallic behavior, where are non-metals predominantly located on the periodic table?
In terms of metallic behavior, where are non-metals predominantly located on the periodic table?
Which type of oxides are typically acidic in nature?
Which type of oxides are typically acidic in nature?
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At standard state conditions (25°C and 1 atm), which element is liquid?
At standard state conditions (25°C and 1 atm), which element is liquid?
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Which type of elements are gases at 25°C and 1 atm?
Which type of elements are gases at 25°C and 1 atm?
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What is the total number of quantum numbers used to describe each electron in an atom?
What is the total number of quantum numbers used to describe each electron in an atom?
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Study Notes
Atoms, Molecules and Structures
- Atoms are the smallest constituents of matter that have the properties of a chemical element.
- Atoms are made up of three fundamental particles: protons, neutrons, and electrons.
Atomic Structure
- Protons and neutrons are found in the nucleus, collectively known as nucleons.
- Electrons are found in spaces outside/around the nucleus, known as orbitals.
Atomic Notation
- Atomic number (Z): whole number of protons (p+) = number of electrons (e-) in a neutral atom.
- Mass number (A): whole number sum of protons and neutrons in an atom.
- Electrons contribute almost no mass to an atom.
- Example: oxygen atom represented as 168𝐸 (8 protons and 8 neutrons).
Isotopes
- Atoms of the same element with different numbers of neutrons are called isotopes.
Quantum Numbers
- Principal quantum number (n): describes the principal energy level with values 1, 2, 3, ….
- Azimuthal/subsidiary quantum number (l): indicates shape of the orbital with values 0, 1, 2, 3, …, n-1.
- Magnetic quantum number (m): indicates direction of the orbital with values ranging from –l to +l.
- Spin quantum number (s): indicates the spin of the electron with values of +1/2 or -1/2.
Distribution of Electrons in Orbitals
- Three rules guide the distribution of electrons in orbitals:
- Aufbau's Principle: electrons fill up the lowest energy orbitals first.
- Hund's Rule of maximum Multiplicity: electrons are filled up singly before pairing.
- Pauli's Exclusion Principle: only two electrons can occupy the same orbital and must do so with opposite spin.
Atomic Orbitals
- There are four atomic orbitals: s, p, d, and f.
- s-orbital:
- only one type with one orientation.
- present in all energy levels (labelled as 1s, 2s, 3s, …, ns).
- spherical in shape.
- p-orbital:
- three degenerate orientations in x, y, and z directions.
- exist in the 2nd and higher energy levels.
- have 3 degenerate orientations in x, y, and z directions (labelled as 2𝑝𝑥, 2𝑝𝑦, 2𝑝𝑧).
- d-orbital:
- five d-orbitals called 𝑑𝑧2 , 𝑑𝑥𝑦 , 𝑑𝑥𝑧 , 𝑑𝑦𝑧 , 𝑑𝑥2−𝑦2.
- double dumb-bell in shape.
- responsible for special properties of transition metals.
- f-orbital:
- seven f-orbitals with complicated shape.
Electronic Configuration
- Arrangement of electrons in orbitals.
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Description
Test your knowledge on topics such as atoms, molecules, states of matter, enthalpies, rates of reactions, acids, bases, oxidation, reduction, and more. Get prepared for your general chemistry course with this comprehensive outline.
