Comprehensive Chemistry Fundamentals

Vocabulary practice flashcards covering atomic structure, periodic trends, chemical bonding, chemical reactions, energetics, stoichiometry, analytical titration techniques, and organic chemistry.

Periodic table

Table of all known elements ordered by atomic number (number of protons).

Atomic number

Number of protons in an atom (equals the number of electrons in a neutral atom).

Mass number

Protons + neutrons in one atom of a particular isotope; always a whole number.

Valence electrons

Electrons in the outermost shell; for Groups 13 to 18 it equals the group number minus 10.

Bohr model

Electrons orbit in shells of fixed energy and cannot exist between shells; higher shells have more energy.

Subshells

$s$, $p$, $d$, $f$ regions within a shell holding 2, 6, 10 and 14 electrons.

Orbital

Region where up to 2 electrons move ($s$ has 1 orbital, $p$ 3, $d$ 5, $f$ 7).

Core charge

Effective positive charge felt by outer electrons; equals the number of valence electrons for main-group elements.

First ionisation energy

Energy needed to remove the most loosely held electron from 1 mole of gaseous atoms, forming $1+$ ions.

Electronegativity

Tendency of an atom to attract the shared electrons in a bond.

Isotopes

Atoms of the same element (same protons) with different numbers of neutrons.

Ionic bond

Electrostatic attraction between oppositely charged ions; forms between a metal and a non-metal.

Ionic lattice

Giant 3D arrangement of alternating cations and anions.

Polyatomic ion

Group of atoms with an overall charge, e.g. $SO_4^{2-}$; treat as one unit.

Metallic bond

Electrostatic attraction between cations and a sea of delocalised electrons.

Delocalised electrons

Outer electrons that are free to move through the whole metal lattice.

Covalent bond

Sharing of electron pairs between non-metal atoms so each has a full valence shell.

Octet rule

Atoms bond to have 8 valence electrons (hydrogen needs 2).

Dipole

Partial charges ($\delta+$ and $\delta-$) in a bond where electrons are shared unequally.

Polar covalent bond

Unequal sharing between different non-metals, e.g. $H-F$ with $F\,\delta-$.

Combination reaction

$A + B \rightarrow C$, e.g. $2Na + Cl_2 \rightarrow 2NaCl$.

Decomposition reaction

$A \rightarrow B + C$, e.g. $CaCO_3 \rightarrow CaO + CO_2$.

Single displacement

$AB + C \rightarrow AC + B$; one element replaces another in a compound.

Double displacement

$AB + CD \rightarrow AD + CB$; two compounds swap partners.

Neutralisation

Acid + base $\rightarrow$ salt + water, e.g. $Mg(OH)_2 + 2HCl \rightarrow MgCl_2 + 2H_2O$.

Precipitation reaction

Two solutions mix to form an insoluble solid (precipitate).

Exothermic reaction

Releases heat to the surroundings, surroundings warm up, $\Delta H$ is negative.

Endothermic reaction

Absorbs heat from the surroundings, surroundings cool down, $\Delta H$ is positive.

Activation energy ($E_a$)

Minimum energy particles need for an effective collision.

Collision theory

Particles must collide with enough energy; more effective collisions per second means a faster rate.

Catalyst

Lowers the activation energy through an alternative pathway; not used up.

Critical elements

Elements in short supply that could run out in 50 to 100 years unless recycled.

Eutrophication

Algal blooms in waterways caused by excess phosphorus from fertiliser.

Mole

$6.02 \times 10^{23}$ particles of a substance.

Avogadro's number

$6.02 \times 10^{23}$ particles per mole.

Molar mass ($M$)

Mass in grams of 1 mole, in $g\,mol^{-1}$; the sum of the atomic masses.

Empirical formula

Simplest whole-number ratio of atoms in a compound.

Molecular formula

Actual number of each atom in one molecule; a whole-number multiple of the empirical formula.

Stoichiometry

Calculating amounts of reactants and products from a balanced equation.

Titration

Finding an unknown concentration by reacting it with a solution of known concentration.

Standard solution

A solution of accurately known concentration.

Aliquot

Exact volume measured by the pipette into the conical flask.

Titre

Volume delivered from the burette.

Equivalence point

Reactants have been added in the exact mole ratio of the equation.

End point

The point where the indicator changes colour.

Concordant titres

Titres within $0.10\,mL$ of each other.

Precision

How closely repeated measurements agree.

Accuracy

How close a result is to the true value.

Random error

Unpredictable variation; reduced by repeating and averaging; affects precision.

Systematic error

Shifts all results the same way; repeating does not fix it; affects accuracy.

Green chemistry

Design of products and processes that reduce or eliminate hazardous substances.

Hydrocarbon

Compound containing only carbon and hydrogen.

Saturated hydrocarbon

Only single carbon-carbon bonds (alkanes).

Unsaturated hydrocarbon

Contains at least one $C=C$ or $C\equiv C$ bond (alkenes, alkynes).

Homologous series

Family with the same general formula and similar properties; each member differs by $CH_2$.

Cracking

Breaking large hydrocarbons over a catalyst into a smaller alkane and an alkene.

Structural isomers

Same molecular formula, different arrangement of atoms.

Addition reaction

Double bond opens and atoms add on: $C_2H_4 + Br_2 \rightarrow C_2H_4Br_2$.

Polymerisation

Many alkene molecules join to form a long chain (a polymer).

Functional group

Atom or group of atoms that gives a compound its characteristic properties.