Grade 9 Chemistry - Complete Unit Flashcards

Comprehensive vocabulary flashcards generated from the Grade 9 Chemistry Student Textbook covering Unit 1 (Chemistry & Its Importance), Unit 2 (Measurements & Scientific Methods), Unit 3 (Structure of the Atom), Unit 4 (Periodic Classification of Elements), and Unit 5 (Chemical Bonding).

Chemistry

The science that deals with the properties, composition, and structure of substances (elements and compounds), the transformations they undergo, and the energy that is released or absorbed during these processes.

Substance

A particular kind of matter with uniform properties, such as gold, silver, water, soap, or table salt.

Matter

A physical substance that occupies space and possesses rest mass.

Physical Chemistry

The branch of chemistry concerned with the study of macroscopic properties, atomic properties, and phenomena in chemical systems.

Organic Chemistry

The branch of chemistry that studies carbon-containing substances.

Inorganic Chemistry

The branch of chemistry that studies substances not primarily based on carbon, commonly found in rocks and minerals.

Analytical Chemistry

The branch of chemistry focused on separating, identifying, and quantifying the chemical composition of matter.

Biochemistry

The branch of chemistry that studies chemical processes occurring within living organisms or living matter.

Geochemistry

The study of the processes that control the abundance, composition, and distribution of chemical compounds and isotopes in geologic environments.

Chemical Physics

A sub-discipline of chemistry and physics that investigates physicochemical phenomena using techniques from atomic and molecular physics and condensed matter physics.

Disinfectants

Chemical agents used to kill microbes present on surfaces such as toilets, floors, and drains.

Analgesics

Painkillers used to achieve relief from pain.

Anesthetics

Drugs that relieve pain to make medical operations more effective.

Antibiotics

Chemical agents used to control infections and cure diseases.

Antiseptics

Chemical agents applied to living tissue to prevent bacterial contamination of wounds.

Tranquilizers

Drugs used to reduce tension and bring calm and peace to patients suffering from mental diseases.

Grand Ethiopian Renaissance Dam (GERD)

A $6,450\,\text{MW}$ hydropower project on the Blue Nile in the Benishangul-Gumuz Region of Ethiopia, located about $30\,\text{km}$ upstream of the border with Sudan.

Industry

An economic activity concerned with the processing of raw materials and the manufacturing of goods in factories.

Measurement

The comparison of a physical quantity to be measured with a unit of measurement that acts as a fixed standard.

Temperature

A physical quantity that measures the intensity of heat, representing the hotness or coldness of a body.

Heat

A form of energy that flows spontaneously from a hotter body to a colder body.

Density

The mass per unit volume of a substance, defined by the formula $d = \frac{m}{V}$.

Systematic Uncertainties

Uncertainties that consistently cause measured values to be too large or too small, which can in principle be identified and eliminated.

Random Uncertainties

Unpredictable variations in measurements that occur without a fixed pattern and can be reduced but never completely eliminated.

Precision

The closeness of agreement among a set of values obtained from identical, repeated measurements of a quantity.

Accuracy

The closeness of a single measured value to the true or accepted value.

Scientific Method

A systematic process used by scientists to investigate, verify, or construct an accurate and reliable understanding of natural phenomena.

Hypothesis

A tentative explanation or educated guess formulated based on observations and collected data prior to experimental testing.

Scientific Theory

A well-tested, broad explanation of natural phenomena based on extensive and repeated experimental evidence.

Abscissa

The horizontal axis or $x$-axis of a graph.

Ordinate

The vertical axis or $y$-axis of a graph.

Atom

The fundamental particle of an element that takes part in a chemical reaction, derived from the Greek word atomos meaning uncuttable or non-divisible.

Law of Conservation of Mass

A fundamental law discovered by Antoine Lavoisier stating that mass is neither created nor destroyed in a chemical reaction; the total mass of products equals the total mass of reactants.

Law of Definite Proportions

A law proposed by Joseph Louis Proust stating that every chemical compound always contains fixed and constant proportions by mass of its constituent elements.

Law of Multiple Proportions

A law stating that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in a ratio of small whole numbers.

Dalton's Atomic Theory

An atomic theory proposed by John Dalton in 1808 stating that all matter is composed of small indivisible atoms, and that all atoms of a given element are identical in mass and size.

Anode Rays (Canal Rays)

Streams of positively charged particles formed in a discharge tube when high-speed cathode ray electrons collide with remaining gas molecules.

Cathode Rays

Streams of negatively charged electrons emitted from the cathode in a vacuum discharge tube operated under high voltage and low pressure.

Electron

A fundamental subatomic particle discovered by J.J. Thomson, carrying a relative charge of $-1$ ($-1.59 \times 10^{-19}\,\text{C}$) and a mass of approximately $9 \times 10^{-31}\,\text{kg}$ ($5.4858 \times 10^{-4}\,\text{amu}$).

Plum Pudding Model

An atomic model proposed by J.J. Thomson in 1904 depicting the atom as a sphere of uniform positive charge embedded with negatively charged electrons.

Proton

A positively charged subatomic particle located in the atomic nucleus, carrying a relative charge of $+1$ ($+1.59 \times 10^{-19}\,\text{C}$) and a mass of $1.0073\,\text{amu}$ ($1.673 \times 10^{-27}\,\text{kg}$).

Planetary Model (Rutherford's Model)

An atomic model proposed by Ernest Rutherford in 1911 describing a small, dense, positively charged nucleus surrounded by electrons revolving in circular paths.

Nucleus

The extremely small, dense central part of an atom containing its protons and neutrons and housing nearly all of the atom's mass.

Bohr's Atomic Model

An atomic model proposed by Niels Bohr in 1913 stating that electrons revolve around the nucleus in stable, fixed circular orbits called stationary energy levels.

Neutron

A neutral subatomic particle located in the nucleus, discovered by James Chadwick in 1932, with a relative charge of $0$ and a mass of $1.0087\,\text{amu}$ ($1.675 \times 10^{-27}\,\text{kg}$).

Atomic Number ($Z$)

The number of protons in the nucleus of an atom, which uniquely identifies a chemical element.

Mass Number ($A$)

The total number of protons and neutrons (nucleons) in the nucleus of an atom, defined as $A = Z + N$.

Isotopes

Atoms of the same element that have the same atomic number (number of protons) but different mass numbers due to varying numbers of neutrons.

Protium

The most abundant isotope of hydrogen ($^1_1\text{H}$), containing 1 proton, 1 electron, and 0 neutrons.

Deuterium

An isotope of hydrogen ($^2_1\text{H}$), containing 1 proton, 1 electron, and 1 neutron.

Tritium

A radioactive isotope of hydrogen ($^3_1\text{H}$), containing 1 proton, 1 electron, and 2 neutrons.

Atomic Mass Unit (amu)

A mass unit equal to exactly $\frac{1}{12}$ the mass of a carbon-12 atom, equivalent to approximately $1.6605 \times 10^{-24}\,\text{g}$ or 1 Dalton (Da).

Average Atomic Mass

The weighted average of the atomic masses of all naturally occurring isotopes of an element based on their natural percent abundances.

Main Energy Level

The principal electron shell relative to the nucleus denoted by the principal quantum number $n$ ($1, 2, 3, 4$ or $K, L, M, N$).

Electronic Configuration

The systematic arrangement of electrons in the various energy levels, shells, or orbitals of an atom.

Valence Shell

The outermost electron shell of an atom that contains electrons.

Valence Electrons

The electrons occupying the outermost electron shell of an atom, which determine its chemical properties and bonding behavior.

Dobereiner's Triads

Groups of three similar elements identified by Johann Wolfgang Döbereiner where the atomic weight of the middle element is approximately the arithmetic mean of the other two.

Newlands' Law of Octaves

A relationship proposed by Alexander Newlands stating that when elements are arranged by increasing atomic weight, the chemical properties repeat every eighth element.

Mendeleev's Periodic Law

A law formulated by Dmitri Mendeleev stating that the physical and chemical properties of elements are periodic functions of their atomic weights.

Modern Periodic Law

A law stating that the physical and chemical properties of elements are periodic functions of their atomic numbers.

Periods

The horizontal rows of elements in the periodic table, where all elements in a row share the same number of electron shells.

Groups

The vertical columns of elements in the periodic table containing elements with the same number of valence electrons and similar chemical properties.

Representative Elements

The main group elements located in Groups IA through VIIA of the periodic table with incompletely filled $s$ or $p$ subshells of the highest principal quantum number.

Atomic Radius

One-half the distance between the nuclei of two adjacent atoms in a metallic lattice or one-half the distance between the nuclei of two bonded identical atoms in a diatomic molecule.

Ionization Energy

The minimum quantity of energy required to remove an electron from an isolated, gaseous atom or ion in its ground state.

Shielding Effect

The reduction in the effective nuclear charge felt by outer valence electrons caused by the electrostatic repulsion of inner-shell core electrons.

Electron Affinity

The energy change in $\text{kJ\,mol}^{-1}$ that occurs when an electron is added to a neutral gaseous atom to form a negative ion.

Electronegativity

A measure of the relative tendency of an atom in a molecule to attract a shared pair of electrons toward itself.

Chemical Bond

An attractive force that holds atoms or ions together to form molecules or compounds.

Octet Rule

A rule proposed by Gilbert N. Lewis stating that atoms tend to gain, lose, or share electrons in order to acquire eight valence electrons and achieve a stable noble gas configuration.

Ion

An atom or group of atoms that carries a net positive or negative electrical charge due to an unequal number of protons and electrons.

Cation

A positively charged ion formed when a neutral atom or group of atoms loses one or more valence electrons.

Anion

A negatively charged ion formed when a neutral atom or group of atoms gains one or more valence electrons.

Ionic Bond

A chemical bond formed through the electrostatic attraction between oppositely charged cations and anions resulting from electron transfer.

Lewis Symbol

A notation in which the chemical symbol of an element is surrounded by dots representing its valence electrons.

Covalent Bond

A chemical bond formed when two atoms share one or more pairs of electrons to achieve electronic stability.

Single Bond

A covalent bond formed when two atoms share one pair of electrons.

Double Bond

A covalent bond formed when two atoms share two pairs of electrons.

Triple Bond

A covalent bond formed when two atoms share three pairs of electrons.

Nonpolar Covalent Bond

A covalent bond formed between two atoms with equal or nearly equal electronegativities, resulting in equal sharing of the bonding electron pair.

Polar Covalent Bond

A covalent bond formed between two atoms with different electronegativities, resulting in an unequal sharing of the bonding electron pair and partial charges ($\delta+$ and $\delta-$).

Coordinate Covalent Bond (Dative Bond)

A covalent bond in which both electrons in the shared bonding pair are provided by a single donor atom.

Metallic Bond

A chemical bond formed by the electrostatic attraction between positive metal cores and a delocalized sea of mobile valence electrons.