5.1 Matter, Elements, Compounds, Mixtures and Chemical Reactions

Matter, Elements, Compounds, Mixtures and Chemical Reactions

Exam Focus: Two distinctions drive nearly every chemistry item on the New York exam: organic versus inorganic, and physical versus chemical change. Learn which salon services fall on each side of the physical/chemical line, because that classification predicts whether a result washes out or is permanent until it grows out.

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1. Fundamentals of Chemistry: Organic vs. Inorganic Chemistry & Matter

Chemistry is the branch of physical science that studies the composition, structure, properties, and reactions of matter, as well as the changes that matter undergoes under various conditions.

                                  CHEMISTRY
                     ┌────────────────┴────────────────┐
                     ▼                                 ▼
             ORGANIC CHEMISTRY                INORGANIC CHEMISTRY
        • Studies carbon-containing matter  • Studies matter lacking carbon
        • Living or once-living substances  • Never alive; minerals, metals
        • Will burn / flammable             • Will NOT burn / non-flammable
        • Examples: Hair color, shampoos,   • Examples: Pure water, hydrogen
          synthetic resins, relaxers          peroxide, iron, pure oxygen

Organic vs. Inorganic Chemistry

• Organic Chemistry: The study of all substances containing the element carbon ($C$). All living things—or substances that were once alive (plants, animals, fossil fuels)—are organic. Organic matter contains carbon-hydrogen bonds and will ignite and burn. In cosmetology, almost all working chemical formulations (permanent hair colors, relaxers, shampoos, conditioners, synthetic nail acrylics, styling polymers) are organic compounds.
• Inorganic Chemistry: The study of all chemical compounds that do not contain carbon. Inorganic substances were never alive, do not contain carbon-hydrogen bonds, and will not burn. Examples in cosmetology include pure distilled water ($H_2O$), hydrogen peroxide ($H_2O_2$), titanium dioxide ($TiO_2$), sodium chloride ($NaCl$), and metal shears.

States of Matter & Molecular Structure

Matter is defined as anything that occupies physical space and has mass (weight). Matter exists in three distinct physical states:

1. Solid: Possesses a definite shape and a definite volume (e.g., ice, manicuring implements, hair clips). Molecular particles are tightly bound in fixed, rigid positions.
2. Liquid: Possesses a definite volume but takes the shape of its container (e.g., shampoos, developers, liquid disinfectants). Molecular particles move freely while remaining in close contact.
3. Gas: Possesses neither a definite shape nor a definite volume; expands indefinitely to fill any container (e.g., propellant gases, ammonia vapor, oxygen). Molecular particles are widely separated and move rapidly.

• Element: The simplest form of chemical matter that cannot be broken down into simpler substances without losing its identity (e.g., Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur—the "COHNS" elements forming human hair).
• Atom: The smallest structural unit of an element that retains all chemical properties of that element.
• Molecules: Formed by chemically combining two or more atoms:
  • Elemental Molecules: Contain two or more atoms of the same element united chemically (e.g., Atmospheric Oxygen: $O_2$, Ozone: $O_3$).
  • Compound Molecules: Contain two or more atoms of different elements united chemically in fixed proportions (e.g., Water: $H_2O$, Hydrogen Peroxide: $H_2O_2$, Table Salt: $NaCl$).

Physical Changes vs. Chemical Changes

┌────────────────────────────────────────┬────────────────────────────────────────┐
│            PHYSICAL CHANGE             │            CHEMICAL CHANGE             │
├────────────────────────────────────────┼────────────────────────────────────────┤
│ • Change in physical form or state     │ • Change in the chemical composition   │
│   without altering chemical identity   │   and molecular structure of a substance│
│ • No new chemical bonds formed         │ • Creates new chemical substances      │
│ • Examples:                            │ • Examples:                            │
│   - Ice melting into liquid water      │   - Disulfide bonds broken by perm     │
│   - Water boiling into steam           │   - Disulfide bonds reformed by neutral│
│   - Temporary color coating hair       │   - Hair color oxidizing with peroxide │
│   - Physical wet setting of hair       │   - Iron rusting into iron oxide       │
└────────────────────────────────────────┴────────────────────────────────────────┘

• Physical Mixtures: A physical combination of two or more substances united physically in any proportion without fixed chemical ratios and without forming new chemical bonds (e.g., salt dissolved in water, air, styling glaze).
• Chemical Compounds: Substances formed by chemical union of two or more elements in definite, fixed proportions that exhibit entirely different chemical and physical properties than their constituent elements.

2. Classifying Salon Services by Type of Change

The physical/chemical distinction is the most useful single idea in cosmetology chemistry, because it tells you in advance whether a result is temporary.

The professional inference matters more than the vocabulary. A physical change can be undone by shampooing; a chemical change cannot be undone at all. That is why a strand test precedes chemical services and never precedes a set.

3. Properties and Salon Chemicals

Physical properties are observed without changing the substance's identity: colour, odour, density, melting point, solubility. Chemical properties describe how a substance reacts — flammability, its reaction with oxygen, its behaviour with acids or bases.

Note the classification that trips candidates: hydrogen peroxide is a compound, not a mixture, but the developer bottle on your shelf is a mixture of hydrogen peroxide, stabilisers, thickeners and a buffering acid.

4. Organic and Inorganic in Practice

Organic chemistry is the chemistry of carbon-containing substances. Almost everything that burns is organic, and almost everything that comes from a living source is organic. Salon examples: thioglycolic acid, aniline derivative dyes, cetyl alcohol, silicones' organic portions, ethyl methacrylate monomer, acetone.

Inorganic chemistry covers substances that contain no carbon: water, metals, pure minerals, ammonia, hydrogen peroxide, sodium hydroxide.

Two exam-relevant consequences:

• Organic solvents are usually flammable. Acetone, alcohols and monomers are why 19 NYCRR § 160.25(b) requires flammable and combustible chemicals to be stored in a metal cabinet remote from ignition sources, and why § 160.12 bans candles, gas burners and cigarettes.
• "Organic" on a product label is a marketing term, not a chemistry term. A product advertised as organic is not thereby gentler, safer or free of allergens. The predisposition test in Chapter 11 is required regardless of how a colour product is marketed.