Chemistry Reviewer: Periodic Table, Trends, Isotopes, and Bonding

Vocabulary flashcards generated from the chemistry lecture notes on periodic table history, periodic trends, isotopes, decay mechanisms, chemical bonding, and nomenclature.

Law of Triads

An organizing system proposed by Johann Wolfgang Döbereiner in $1829$ that grouped elements with similar chemical properties into sets of three, demonstrating that the atomic weight of the middle element was approximately the arithmetic mean of the other two.

Law of Octaves

An arrangement created by John Alexander Newlands in $1864$ ordering elements by increasing atomic mass, where every $8\text{th}$ element exhibited similar properties, similar to musical octaves.

Dmitri Mendeleev

A Russian chemist known as the Father of the Periodic Table who arranged elements by increasing atomic mass and predicted the properties of undiscovered elements by leaving blank spaces in his table.

Eka-

A prefix coming from the Sanskrit word meaning 'one,' used by Mendeleev to name predicted, undiscovered elements located one position below a known element in his periodic table.

Eka-boron

An undiscovered element predicted by Mendeleev that was later discovered as Scandium (atomic number $21$).

Eka-aluminum

An undiscovered element predicted by Mendeleev that was later discovered as Gallium (atomic number $31$).

Eka-silicon

An undiscovered element predicted by Mendeleev that was later discovered as Germanium (atomic number $32$).

Eka-manganese

An undiscovered element predicted by Mendeleev that was later discovered as Technetium (atomic number $43$).

Modern Periodic Law

The law established following Henry Moseley's work in $1913$ stating that the chemical and physical properties of elements are periodic functions of their atomic numbers.

Atomic Radius

The average distance from the center of the nucleus to the outermost electron of an atom, representing its effective size measured in picometers ($\text{pm}$).

Ionization Energy

The minimum amount of energy (in $kJ/mol$) required to remove one electron from a neutral atom in its ground gaseous state.

Electron Shielding

The reduction in the nucleus's attractive pull on outer valence electrons caused by the presence of inner-shell electrons.

Electron Affinity

The energy change that occurs when a neutral, isolated gaseous atom gains an extra electron.

Electronegativity

The ability or tendency of an atom to attract shared (bonding) electrons toward itself in a chemical bond.

Coulomb's Law

The principle stating that oppositely charged particles attract each other, whereas similarly charged particles repel each other.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Radioisotopes

Unstable forms of isotopes with an imbalanced ratio of protons and neutrons that spontaneously undergo radioactive decay to emit energetic radiation.

Alpha Decay

A form of radioactive decay involving the emission of an alpha particle ($\text{a}$) from a heavy, unstable atomic nucleus.

Beta-Plus Decay

A type of beta decay where a proton converts into a neutron, releasing a positron and a neutrino.

Beta-Minus Decay

A type of beta decay where a neutron converts into a proton, releasing an electron and an antineutrino.

Gamma Decay

The emission of high-energy electromagnetic radiation in the form of photons (gamma rays, $\text{y}$) from an unstable atomic nucleus.

Half-Life

The time required for half of the radioactive atoms in a sample to decay, modeled by the formula N(t) = N_0 \times \begin{pmatrix}\frac{1}{2}\begin{pmatrix}^{t / t_{1/2}}.

Valence Electrons

The electrons in the outermost shell or energy level of an atom that participate in chemical bonding.

Lewis Dot Symbol

A representation consisting of an element's chemical symbol surrounded by dots representing its valence electrons.

Octet Rule

The principle stating that atoms lose, gain, or share electrons during chemical bonding to achieve a stable outer shell of $8$ valence electrons.

Ionic Bonding

A chemical bond formed via the full transfer of electrons from a metal atom to a non-metal atom due to a large electronegativity difference.

Polar Covalent Bond

A covalent bond formed between non-metals characterized by an unequal sharing of electrons, causing partial electron transfer and shifted electron density.

Non-Polar Covalent Bond

A covalent bond in which electrons are shared equally between atoms, resulting in a balanced distribution of electrical charge.

Duet Rule

An exception to the octet rule where very light elements, specifically hydrogen and helium, achieve stability with exactly $2$ valence electrons.

Expanded Octet

An exception to the octet rule occurring in elements located in the third row of the periodic table and beyond, enabling them to accommodate more than $8$ valence electrons.

Resonance Structure

One of two or more valid Lewis structures for a single molecule that cannot be represented accurately by a single Lewis structure alone.

Molecular Formula

A chemical formula that represents the exact actual number of atoms of each element in a molecule, such as $C_6H_{12}O_6$ for glucose.

Empirical Formula

A chemical formula showing the simplest whole-number ratio of the atoms present in a compound.

Oxoacids

Acids that contain hydrogen, oxygen, and another central element.