chem paper 1

Periodic Table

A tabular arrangement of elements based on their atomic number and properties.

Metals

Elements that are typically shiny, good conductors of heat and electricity, and malleable.

Non-Metals

Elements that are typically dull, poor conductors of heat and electricity, and brittle.

Compounds

Substances formed when two or more elements combine chemically in fixed proportions.

Mixture

A combination of two or more substances that do not chemically bond and retain their own properties.

Filtration

A method to separate an insoluble solid from a liquid using a filter.

Crystallisation

A process used to separate a dissolved solid from a solvent, forming crystals.

Simple Distillation

A technique used to separate a liquid from a solution based on boiling point.

Fractional Distillation

A process to separate mixtures of liquids with different boiling points using a fractionating column.

Chromatography

A technique used to separate mixtures based on the movement of substances through a medium.

Separation Funnel

An apparatus used to separate immiscible liquids based on their densities.

Plum-Pudding Model

An early model of the atom suggesting it is a ball of positive charge with negative electrons embedded.

Nuclear Model

An atom model proposing that electrons orbit a dense nucleus of protons and neutrons.

Protons

Positively charged particles found in the nucleus of an atom.

Neutrons

Neutral particles found in the nucleus of an atom.

Electron

A negatively charged particle that orbits the nucleus of an atom.

Relative Atomic Mass

The average mass of an element's isotopes, taking into account their relative abundances.

Isotopes

Atoms of the same element that have different numbers of neutrons.

Ions

Charged particles formed when an atom loses or gains electrons.

Oxides

Compounds formed from the reaction of a metal or non-metal with oxygen.

Ionic Compound

Compounds formed from the transfer of electrons between metals and non-metals.

Molecular Compound

Compounds formed from the sharing of electrons between non-metals.

Solute

A substance that is dissolved in a solvent to form a solution.

Solvent

A substance that dissolves a solute to form a solution.

Solution

A homogeneous mixture formed when a solute is dissolved in a solvent.

Miscible

Liquids that mix together uniformly.

Immiscible

Liquids that do not mix together.

Soluble

A substance that can be dissolved in a solvent.

Insoluble

A substance that cannot be dissolved in a solvent.

Group 1 Elements

Elements known as Alkali metals, characterized by having one electron in their outer shell.

Group 7 Elements

Elements known as Halogens, characterized by having seven electrons in their outer shell.

Diatomic Molecules

Molecules composed of two atoms, such as Cl2 and Br2.

Alkali Metals

Group 1 metals that are soft, have low density, and react vigorously with water.

Halogens

Group 7 nonmetals that are reactive and form salts with metals.

Transition Metals

Elements in groups 3-12 of the periodic table, known for their high density and melting points.

Catalyst

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

Flame Test

A test used to identify the presence of certain metals based on the color of the flame produced.

Noble Gases

Group 18 gases that are unreactive due to having a full outer shell of electrons.

Chemical Properties

Characteristics that describe how a substance interacts in reactions.

Physical Properties

Characteristics that can be observed without changing the composition of a substance.

Boiling Point

The temperature at which a liquid becomes a gas.

Melting Point

The temperature at which a solid becomes a liquid.

Density

Mass per unit volume of a substance.

Reactivity Series

A list of metals arranged in order of their reactivity with other substances.

Atomic Number

The number of protons in the nucleus of an atom, defining the element.

Mass Number

The total number of protons and neutrons in the nucleus of an atom.

Electron Configuration

The distribution of electrons among the energy levels of an atom.

Valence Electrons

Electrons in the outermost shell of an atom that determine its chemical properties.

Chemical Reaction

A process that involves the transformation of one or more substances into different substances.

Electron Shells

Energy levels where electrons reside around the nucleus of an atom.

Alkaline Earth Metals

Group 2 metals that have two electrons in their outer shell.

Trends in Reactivity

Patterns of reactivity observed when moving down a group in the periodic table.

Chemical Bonds

Forces that hold atoms together in compounds, including ionic and covalent bonds.

Periodic Trends

Patterns in properties such as atomic radius, ionization energy, and electronegativity in the periodic table.

Octet Rule

The principle that atoms tend to gain, lose, or share electrons to achieve a full outer shell of eight electrons.

Crystal Lattice

A three-dimensional arrangement of atoms in a crystalline solid.

Molecular Structure

The arrangement of atoms within a molecule.

Hydroxides

Compounds formed when hydroxide ions combine with metals.

Salt

An ionic compound formed from the reaction of an acid with a base.

Electrolysis

A process that uses electricity to cause a chemical change, typically to decompose a compound.

Ionic bonding

The electrostatic attraction between positive and negative ions.

Giant lattice

A regular structure that extends in all directions in a substance that holds ionic compounds together.

High melting and boiling point

Properties of ionic substances due to strong electrostatic forces between oppositely charged ions.

Conductivity of ionic substances when solid

Ionic substances do not conduct electricity when solid because ions are in fixed positions.

Conductivity of ionic compounds when molten or dissolved

Ionic compounds conduct electricity when molten or dissolved because ions are free to move.

Positive ions examples

Examples include Na+, Mg2+, Al3+, Ca2+, Rb+.

Negative ions examples

Examples include Cl−, Br−, SO4 2−, NO3 −, OH−.

Electrically neutral ionic compounds

Ionic compounds are neutral as positive and negative charges balance each other.

Formation of ionic compounds

Ionic compounds are formed by the transfer of electrons from metals to non-metals.

Mg in ionic bonding

Magnesium gives away its 2 outer shell electrons to oxygen in ionic bonding.

Characteristics of simple molecular covalent substances

Do not conduct electricity, consist of small molecules with weak intermolecular forces.

Effect of increasing molecular mass on intermolecular forces

Intermolecular forces increase with mass/size of the molecule, leading to higher melting/boiling points.

Polymers

Very large molecules with atoms linked by covalent bonds.

Thermosoftening polymers

Polymers that melt or soften when heated due to weak intermolecular forces.

Giant covalent substances

Solids formed by atoms covalently bonded in a giant lattice, often with high melting and boiling points.

Diamond properties

Diamond has strong covalent bonds, is very hard, and has a very high melting point.

Graphite properties

Graphite has three covalent bonds per carbon atom, conducts electricity, and is soft due to layered structure.

Fullerenes

Hollow shaped molecules based on hexagonal rings, which may have pentagonal or heptagonal structures.

Nanotubes

Cylindrical fullerenes with high length to diameter ratio, known for high tensile strength and conductivity.

Graphene

A single layer of graphite known for its exceptional electrical and thermal conductivity.

Metals' properties

Metals have high melting/boiling points, conduct heat and electricity, and are malleable.

Alloys definition

Mixtures of metals with other elements that are harder than pure metals due to distorted layers.

Limitations of the simple model

The simple model does not account for forces between spheres or the true nature of atoms, molecules, and ions.

Energy to change states

Depends on the strength of forces between particles and the type of bonding and structure.

Pure substance properties

A pure substance will melt or boil at a fixed temperature, while a mixture melts over a range.

Uses of nanoparticles

Applications include medicine, electronics, deodorants, and sun creams for better protection.

Fine and coarse particles

Fine particles range from 100-2500 nm in diameter, whereas coarse particles range from 2500-10,000 nm.

Nanoparticles' unique properties

Nanoparticles exhibit different properties than bulk materials due to their high surface area to volume ratio.

Law of Conservation of Mass

States that no atoms are lost or made during a chemical reaction; the mass of the products equals the mass of the reactants.

Relative Atomic Mass (RAM)

Average mass of atoms in an element, considering the masses and abundance of its isotopes relative to 12C.

Relative Formula Mass (RFM)

Sum of the relative atomic masses of all atoms in a compound's formula.

Balanced Chemical Equation

An equation that shows the reactants and products in a chemical reaction and their respective quantities.

Avogadro's Constant

The number of atoms, molecules or ions in a mole of a substance, equal to 6.02 x 10^23.

Limiting Reactant

The reactant that is completely used up in a chemical reaction, limiting the amount of product produced.

Molar Volume of a Gas

1 mole of a gas occupies 24 dm3 at room temperature and pressure.

Titration

A technique for determining the concentration of a solution by reacting it with a solution of known concentration.

Percentage Yield

% Yield = (Actual mass of product / Maximum theoretical mass of product) x 100%.

Atom Economy

A measure of the proportion of reactants that become useful products, calculated by the relative formula mass of desired products over the sum of relative formula masses of all reactants.

Mean Mass

The average mass calculated from multiple trials.

Concentration Formula (mass/g)

Concentration = Mass (g) / Volume (dm3).