Science Study Notes: Chemical Reactions, Genetics, Waves and Motion

Comprehensive vocabulary flashcards covering key terms and concepts across Chemical Reactions, Nuclear Chemistry, Genetics, and Waves and Motion from the study checklist.

Law of Conservation of Mass

The scientific principle stating that mass is conserved during a chemical reaction, meaning the total mass of the reactants equals the total mass of the products.

Open System

A system where matter and energy can be exchanged with the environment, which can cause mass to appear to change during a chemical reaction.

Closed System

A system that prevents matter from entering or escaping, ensuring that total mass is strictly conserved during a chemical reaction.

Reactants

The initial chemical substances present before a chemical reaction occurs that are converted into products.

Products

The new substances that are formed as a result of a chemical reaction.

Word Equation

A chemical equation that represents a chemical reaction using the names of the reactants and products.

Chemical Equation

A representation of a chemical reaction using chemical formulas, state symbols, and coefficients to demonstrate the conservation of mass.

Synthesis Reaction

A chemical reaction where two or more simpler substances combine to form a single, more complex product.

Decomposition Reaction

A chemical reaction in which a single compound breaks down into two or more simpler substances.

Rusting

A specific type of corrosion reaction where iron or steel reacts with the environment, causing material degradation.

Corrosion

A chemical process that gradually deteriorates and weakens materials through reactions with their surrounding environment.

Displacement Reaction

A chemical reaction in which one element or ion displaces another within a compound, classified into single-displacement and double-displacement reactions.

Precipitate

An insoluble solid that forms and separates out of a liquid solution during a chemical reaction, predictable via solubility rules.

Acid

A corrosive substance with a pH less than $7$ that reacts with bases, metals, and carbonates.

Base

A caustic substance with a pH greater than $7$ that reacts with and neutralises acids.

Alkali

A water-soluble base with a pH greater than $7$.

Neutralisation Reaction

A chemical reaction between an acid and a base that produces a salt and water.

Collision Theory

The scientific theory stating that chemical reactions occur when reacting particles collide with sufficient activation energy and correct orientation.

Catalyst

A substance that increases the rate of a chemical reaction without being permanently consumed in the process.

Big Bang Theory

The scientific model explaining the origin and expansion of the universe, supported by evidence such as redshift.

Redshift

The phenomenon where the wavelength of light from distant celestial objects is stretched toward the red end of the spectrum, providing evidence for an expanding universe.

Isotope

Atoms of the same element that have the same number of protons but different numbers of neutrons; unstable isotopes are radioactive.

Radioactive Decay

The spontaneous process by which unstable radioactive isotopes emit particles or energy, such as alpha, beta, and gamma radiation, to become more stable.

Half-Life

The time required for half of the radioactive nuclei in a sample to undergo radioactive decay, used in scientific radiometric dating.

Nuclear Fission

A nuclear reaction where a heavy nucleus splits into smaller nuclei, releasing energy and potentially initiating a self-sustaining chain reaction.

Nuclear Fusion

A nuclear reaction where two light atomic nuclei combine to form a heavier nucleus, releasing massive amounts of energy.

DNA

Deoxyribonucleic acid; the double-helix molecule made of nucleotides that stores hereditary genetic information and replicates during cell division.

Gene

A discrete segment of DNA arranged on a chromosome that encodes the instructions for a specific trait or function.

Chromosome

A thread-like structure composed of tightly coiled DNA and proteins that organizes genetic material inside cells.

Genotype

The specific genetic makeup or combination of alleles of an organism (such as homozygous or heterozygous).

Phenotype

The observable physical and physiological traits of an organism resulting from the interaction of its genotype with the environment.

Mitosis

The process of cell division that produces two genetically identical diploid cells for growth and repair.

Meiosis

The process of reduction cell division that produces four genetically diverse haploid gametes for sexual reproduction.

Gamete

A haploid sex cell, such as a sperm or an ovum (egg), that unites during fertilisation in sexual reproduction.

Binary Fission

A form of asexual reproduction in single-celled organisms where one parent cell divides into two genetically identical daughter cells.

Crossing Over

The exchange of genetic segments between homologous chromosomes during meiosis, creating new allele combinations and genetic variation.

Mutation

A permanent change in the nucleotide sequence of DNA that creates new genetic variation and diversity.

Dominant Allele

An allele that determines the phenotype in both homozygous and heterozygous states in Mendelian inheritance patterns.

Recessive Allele

An allele whose phenotypic effect is masked in the presence of a dominant allele and is only expressed when homozygous.

Homozygous

Having two identical alleles for a specific gene in an organism's genotype.

Heterozygous

Having two different alleles for a specific gene in an organism's genotype.

Punnett Square

A grid diagram used to predict the possible genotypes and phenotypes of offspring and calculate inheritance ratios.

Pedigree Chart

A chart showing family relationships used to track the inheritance of genetic traits across generations.

Selection Pressure

Biotic and abiotic environmental factors that influence which individuals in a population are more likely to survive and reproduce.

Natural Selection

Darwin's mechanism of evolution where organisms with traits best suited to their environment survive, reproduce, and pass those favourable traits to subsequent generations.

Homologous Structures

Anatomical structures in different species that share a similar basic framework due to inheritance from a common ancestor.

Vestigial Structures

Reduced anatomical structures that have lost most or all of their ancestral function, providing evidence for evolutionary change.

Wave

A repeating disturbance that transfers energy from one place to another without transferring matter.

Transverse Wave

A wave in which particle vibrations occur perpendicularly to the direction of energy propagation, characterised by crests and troughs.

Longitudinal Wave

A wave in which particle vibrations occur parallel to the direction of energy propagation, characterised by compressions and rarefactions.

Mechanical Wave

A wave that requires a material medium (such as a solid, liquid, or gas) to propagate energy, such as a sound wave.

Electromagnetic Wave

A wave capable of travelling through a vacuum without a physical medium, including radio waves, visible light, and X-rays.

Wave Equation

The relationship $v = f\times\beta$ or $v = f\times\beta$ usually stated as $v = f\times\beta$, specifically $v = f\times\beta$, where wave speed ($v$) equals frequency ($f$) multiplied by wavelength ($\beta$), represented as $v = f\beta$.

Doppler Effect

The observed change in the frequency or pitch of a wave when the source of the wave and the observer are moving relative to each other.

Ultrasound

High-frequency sound waves that exceed the normal upper limit of human hearing, used in medical imaging and therapeutics.

Law of Reflection

The physical rule stating that the angle of incidence is equal to the angle of reflection when a wave reflects off a surface.

Refraction

The bending of a wave's path caused by a change in speed when it transitions between media of different optical densities.

Displacement

A vector quantity measuring the straight-line distance and direction from an object's starting position to its final position.

Velocity

The rate of change of displacement with respect to time, representing speed with a specified direction.

Acceleration

The rate at which an object changes its velocity over time, including speeding up, slowing down (deceleration), or changing direction.

Inertia

The natural tendency of an object to resist changes in its state of rest or uniform motion, explained by Newton's First Law.

Newton's First Law

The law of motion stating that an object will remain at rest or continue moving at constant velocity unless acted upon by an unbalanced net force.

Newton's Second Law

The law of motion establishing that an object's acceleration is directly proportional to the net force acting on it and inversely proportional to its mass, expressed as $F = ma$.

Newton's Third Law

The law of motion stating that whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.

Vector

A quantity that requires both a magnitude (size) and a direction to be completely described, such as force, displacement, or velocity.

Net Force

The overall resultant vector force acting on an object, calculated by summing all individual forces acting in the same or opposing directions.