Matter, Solutions, and Solubility Curves

Unit 1: Matter

• A solubility curve graphs solubility (g/100g water) against temperature (°C).
• The curves allow substance comparisons.
• Insoluble substances, like sand in water, do not dissolve regardless of stirring or heating.
• Soluble substances, like salt and sugar, dissolve in water to form solutions via solvent-solute particle collisions.
• Heating/cooling curves help determine melting and boiling points.
• Impurities lower the melting and boiling points of pure substances; this is used as a purity test.
• A solute dissolves to make a solution (e.g., salt in salt solution).
• A solvent dissolves the solute (e.g., water in salt solution).
• Suspensions are heterogeneous mixtures that separate over time.
• Colloids are mixtures where one substance is evenly dispersed in another, between solutions and suspensions.
• The dispersed phase in colloids includes particles larger than molecules but invisible to the naked eye.

Classifying Matter

• Matter can be classified as pure elements, pure compounds, mixtures of elements, mixtures of compounds, or mixtures of both.
• Elements are substances like oxygen, consisting of only one type of atom.
• Compounds are substances like carbon dioxide, consisting of two or more chemically bonded elements.
• Mixtures are combinations of substances like oxygen and helium and ethanol and water that are physically combined
• Filtration separates an insoluble solid from a liquid (e.g., chalk and water).
• Evaporation separates a solute from a solvent (e.g., salt from water).
• Simple distillation separates two miscible liquids with different boiling points.
• Chromatography separates colors (e.g., chlorophyll).
• Solids have particles that are very close, arranged in a regular pattern, vibrate in place, and possess low energy.
• Liquids have particles that are close, arranged randomly, move around each other, and possess greater energy
• Gases have particles that are far apart, arranged randomly, move quickly in all directions, and possess the highest energy.

The Periodic Table

Calculating Subatomic Particles

• An element's symbol shows its mass number (top) and atomic number (bottom).
• Number of protons equals the atomic number.
• Number of electrons is the same as the atomic number.
• The neutron number is the mass number minus the atomic number

Atomic Structure

• Atoms have a central nucleus surrounded by electrons in shells.
• Protons are positively charged and electrons are negatively charged .
• Electrons occupy energy levels (shells) outside the nucleus.
• Shells hold different numbers of electrons.
• Electrons fill the lowest energy level (closest to the nucleus) first.

Isotopes

• Isotopes are elements with the same proton number but different neutron numbers, resulting in the same atomic number but different mass numbers.

Atomic and Mass Number

• Atomic Number (Z): The number of protons.
• Mass Number (A): The sum of protons and neutrons.

Relative Atomic Mass (RAM)

• The average mass of its atoms, relative to 1/12th the mass of carbon-12, is calculated from the mass numbers and abundance of all isotopes.
• Chlorine exists as Chlorine-35 (75%) and Chlorine-37 (25%).
• The Ar of chlorine = 35.5

Periodic Table Groups

• Group 1 (Alkali Metals): Vertical column on the far left; alkali metals
• Group 7/17 (Halogens): Vertical column on the right; halogens (non-metals)
• Group 0/8/18 (Noble Gases): Vertical column on the far right; noble gases (non-metals)
• Horizontal = Periods: 7 periods; elements have the same occupied electron shells; metal to non-metal properties from left to right.
• Vertical = Group: 18 groups; share properties; atoms have the same electrons in their outer shell.
• Elements are placed according to properties like atomic radius, metallic nature, chemical reactivity, ion formation, and acid-base character.

Metals and Non-Metals

• Metals are mostly shiny, solid at room temperature, have high density, are strong, malleable, good electricity conductors, and form basic/alkaline oxides.
• Non-metals are dull, can be solid/gas/liquid, have low density, are weak, brittle, poor conductors, and form acidic oxides.

Structure of Bonding

Ionic Formulae

• Ionic bonding is the attraction between + and – ions, forming when metallic atoms give electrons to non-metallic atoms.
• Ionic compound formulae balance positive and negative charges for overall neutrality.
• Example: Barium Chloride (BaCl2) formation
• Balance charges with + and - ions.
• Write the + (metal) ion first, then the - ion: Ba2+ Cl- Cl-
• Add subscripts to indicate required ions: BaCl2

Giant Covalent Structures

• Giant covalent structures contain atoms joined to adjacent atoms by covalent bonds in a giant lattice.
• Exhibit strong structures.
• Metallic Bonding
• Bonding in metal structures is due to delocalized electrons. Exhibiting electrical and thermal conductivity, malleability, ductility, and shiny texture.

Naming Ionic Compounds

• Determine if the compound consists of a metal and a non-metal.
• Covalent compounds have the metal cation name + non-metal anion with suffix ide.
• Ionic compounds must be assessed for the presence of hydrogen and oxygen.
• Oxyacids (contain H and O): named by removing 'hydrogen,' changing suffix (-ate to -ic or -ite to -ous), and adding 'acid.'
• Binary acids (contain H only): named by changing hydrogen to hydro- and adding -ic to the other element's suffix

Simple Covalent Molecules

• They contain only a few atoms held together by covalent bonds.
• An example is CO2
• Exhibit Low melting and boiling points due to weak intermolecular forces; liquids or gases at room temperature.
• Do not conduct electricity because they don't have free electrons or overall charge.

Ionic Compounds

• Ionic Compounds consist of strong electrostatic forces and have giant ionic lattices.

Metals Alloys properties

• Distorted layers of atoms in alloys with different sized atoms require greater force.
• Alloys are stronger and harder metals.

Acids, Bases & Alkalis

• Acids form hydrogen ions (H+) solutions in water, with pH values less than 7 (e.g., HCl(aq) → H+(aq) + Cl-(aq)).
• Alkalis form hydroxide ions (OH−) solutions in water, with pH values greater than 7 (e.g., NaOH(aq) → Na+(aq) + OH−(aq)).
• Neutral solutions has pH=7.

Reactions of acid reactions

• Acids react with metal oxides/hydroxides/alkalis/metal carbonates to form Salt + Water (or Salt + Water + Carbon Dioxide).

Precipitation reactions

• Precipitation = substances in solution mix to form an insoluble solid (precipitate).
• The pH scale measures acidity/alkalinity. Probes measure pH.
• Universal indicator estimates pH through color.
• Acid rain destroys plants and erodes buildings by releasing of acidic gases, which pollute and corrodes landscapes.
• Nitrogen dioxide (NO2) is created by sparking nitrogen/oxygen in car engines and lighting storms.

Acids bases and Alkalis - Salt and Energy Changes

• Salt Formation
• Soluble salts form from reacting acids with metals, metal oxides, or carbonates.
• Energy Changes
• Neutralization is exothermic, increasing temperature until reactants are used, decreasing temperature.
• Bases (metal oxides or hydroxides) neutralize acid (e.g., CuO(s) + 2HCl(aq) -> CuCl2(aq) + H2O(1)).
• Ocean Acidification
• Acidification causes environmental impacts, reactions with calcium carbonate in marine shells, reduced biodiversity.

Energetics and Kinetics

• In kinetic reactions, collision theory states particles must collide with correct orientation and sufficient energy.
• increased frequency of particle collisions = increase reaction rate
• Factors: surface area, catalysts, and concentration affect the reaction rate.
• Rate of Reaction = (Quantity of reactant used / product formed) / Time taken
• Calorimetry: Q=MCAT
• Calculate amount of heat released/absorbed (energy transfer): energy transferred (joules) = mass of water (grams) x specific heat capacity x temperature change (K or ºC)
• To enable reactions to take place, bonds in reactants must first break. The atoms can then rearrange, and new bonds can then form to form products.
• endothermic bond breaking requires energy.
• exothermic bond forming release energy.

Energetics and Kinetics - Factors Affecting Rates and Catalysis

• Temperature and catalysts affect the rate of a reaction.
• Increasing temperature increases kinetic energy increases frequency of particle collisions; a greater collision proportion reacts.
• Catalysts speeds up chemical reactions without being consumed by providing a new route (lower Ea) to lower the energy barrier..
• Heterogeneous catalysis catalysts are used from different phases.
• Homogenous catalysis is catalysts that have everything present in the same phase.
• Combustion: exothermic fuel burning; releases stored energy from fossil fuel.

Chemical Calculations

• The molar mass and molar volume are important concepts in chemistry for converting between mass, moles, and volume of substances.
• Using chemical formulas, percentage composition defines percentage of chemical: % mass = (Total Ar of the element : Mr of the compound) × 100
• Empirical formulas define simplest whole number ratio of atoms, calculated using experimental data.

Chemical reactivity of metals

Reactions of Metals with Acids

• Metal + water = metal hydroxide + hydrogen (e.g., 2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g) )
• Reactivity increases reaction rate.
• Reactions of Metals with Dilute Acids:
• Metal + dilute acid = salt + hydrogen (e.g., Mg(s) + 2HCl(aq) = MgCl2(aq) + H2(g))
• Reactions of Metals with Oxygens:
• Metals react with oxygen = basic metal oxides (neutralize acids) with an example of aluminum + iron (III) oxide = iron + aluminum oxide
• Displacement Reactions:
• More reactive metals displace less reactive from compounds. For example, magnesium displaces copper from copper sulfate to form magnesium sulfate + copper

Chemical Reactivity - Electrolysis and Fuel Cells

• Reactive metals are extracted from ores through electrolysis
• Aluminium extraction involves large-scale electrolysis
• Electrolysis-decomposes ionic substances into simpler when electricity passes through; extracts and purifies metals.
• Fuel Cells- fuels react with oxide in controlled manner, generating electricity more efficiently than combustion with fewer moving parts.
• Electrochemical cells, batteries-electrochemical cells use dipping 2 electric metals, which increases the voltage produces.

Organic Chemistry

• Organic chemistry is the study of carbon compounds.
• Due to Its versatility, over a million carbon compounds are known .
• Carbon bonding forms diverse carbon-carbon and carbon-heteroatom with -OH functional groups.
• Alkanes are a series of saturated hydrocarbons with general formula CnH2_n+2.
• Similar properties and trends exist together within in homologous series.
• Saturated hydrocarbons are joined with single bonds, and unreactive with oxygen in the air (combustion).
• Cracking alkanes reactions larger saturates hydrocarbon, broken into smaller molecules: the starting materials are alkanes & products are alkanes / alkenes.
• During fermentation, enzymes in yeast convert sugar (glucose) into ethanol and carbon dioxide around 30°C.

Organic Chemistry - Alkenes and Polymers

• Alkenes are hydrocarbons with C=C double bonds, having a homologous and unsaturated structure.
• Polymers include large numbers of polymers naturally occur in living things and can be made through chemical processes.
• Different polymer properties determine different uses.
• All-natural polymers are condensation polymers monomers contain two groups.
• All monomers contain two types of functional groups, every time a water line is formed one time the links made in the monomers.

Organic Chemistry - Plastics

• Low-density plastics contain branching; Thermosetting plastics improve strengt through covalent crosslinks between chains.
• Fractional distillation separates crude oil into fractions with close boiling points.
• The carbon footprint is the amount of emitted carbon by a community when perfroming certain amounts of activities.
• This carbon footprint is reduced through reduced pollutants.
• In the carbon cycle, solar energy powers photosynthesis and converts energy within the cycle.