GOB Chemistry Chapter 1: Matter and Measurement Study Notes

Chemistry in Health Sciences

Importance of Chemistry for Nursing and Health Professions

Chemistry is fundamental for understanding the relationships between molecules and the human body, especially at the cellular level. It underpins physiology, pathophysiology, and pharmacology, which are essential for assessing, treating, and monitoring patients.

• Key Point: Chemistry explains biological processes such as energy production, respiration, blood types, and nutrition.

• Application: Understanding chemistry helps explain why foods and vitamins are important and how body systems function together.

Classification of Matter

Types of Matter

Matter is anything that occupies space and has mass. It can be classified as pure substances or mixtures.

• Pure Substances: Consist of only one type of substance and can be represented by a chemical formula or symbol.

• Mixtures: Combinations of two or more substances that can be separated into their components.

Elements and Compounds

Pure substances are further classified as elements or compounds.

• Element: The simplest type of matter, made up of only one type of atom.

• Atom: The smallest unit of matter that retains its unique characteristics.

• Compound: A pure substance made of two or more elements chemically joined together.

• Example: Water ($H_2O$) and sodium chloride ($NaCl$) are compounds; gold (Au) and oxygen (O) are elements.

Mixtures: Homogeneous and Heterogeneous

Mixtures can be homogeneous or heterogeneous.

• Homogeneous Mixture: Composition is uniform throughout (e.g., air, vodka).

• Heterogeneous Mixture: Composition is not uniform and varies throughout (e.g., sand, salad).

Atomic Structure

Bohr Model of the Atom

The Bohr Model describes atoms as having a nucleus containing protons (positive charge) and neutrons (no charge), with electrons (negative charge) orbiting the nucleus in shells.

• Electron Shells: Electrons occupy shells (energy levels) around the nucleus: K (n=1), L (n=2), M (n=3).

• Planetary Model: Electrons orbit the nucleus like planets around the sun.

Electron Configuration and the Octet Rule

Electrons fill orbitals in a consistent order, with atoms being most stable when their outermost shell (valence shell) contains eight electrons (octet rule).

• First Shell: Maximum of 2 electrons.

• Second and Third Shells: Maximum of 8 electrons each.

• Octet Rule: Atoms are energetically stable with 8 electrons in their valence shell (except for the innermost shell).

Electron Distribution Principles

• Aufbau Principle: Electrons fill the lowest energy orbitals first ($1s < 2s < 2p < 3s < 3p < 3d$).

• Pauli Exclusion Principle: No more than two electrons can occupy an atomic orbital.

• Hund's Rule: Electrons fill empty degenerate orbitals before pairing up.

The Periodic Table

Organization of the Periodic Table

The periodic table lists all known elements, each represented by a chemical symbol. Elements are organized by atomic number and grouped by similar chemical properties.

• Groups: Vertical columns with similar chemical behaviors. Main-group elements are labeled with 'A', transition elements with 'B', or by numbers 1-18 (IUPAC).

• Periods: Horizontal rows numbered 1-7.

• Metals, Nonmetals, Metalloids: The staircase line separates metals from nonmetals; elements bordering the line (except Al) are metalloids.

Elements Essential for Human Health

• Macronutrients: Needed in quantities >100 mg/day (e.g., Na, Mg, K, Ca, Cl).

• Micronutrients: Needed in quantities <100 mg/day (e.g., I, F, Fe, Zn).

• Example: Iron is found in hemoglobin; iodine is important for thyroid hormones; fluoride is important for teeth and bones.

Chemical Formulas and Compounds

Chemical Formulas

Chemical formulas indicate the elements present and the number of atoms of each in a compound.

• Example: $H_2O$ (water) has two hydrogen atoms and one oxygen atom.

• Example: $NaCl$ (table salt) has one sodium atom and one chlorine atom.

Physical and Chemical Changes

Physical Change

A physical change alters the state or appearance of matter without changing its identity.

• Examples: Boiling water, dissolving sugar, melting ice.

Chemical Change

A chemical change results in the formation of new substances with different chemical identities. This is called a chemical reaction.

• Examples: Burning wood, digestion, rusting iron, baking a cake.

Chemical Equations

Chemical equations represent chemical reactions, showing reactants and products. The equation must be balanced to obey the law of conservation of mass.

• General Form: $\text{Reactants} \rightarrow \text{Products}$

• Physical States: Indicated by (s)olid, (l)iquid, (g)as, or (aq)ueous.

• Balancing Equations: Add coefficients to ensure the same number of atoms of each element on both sides.

Measurement in Chemistry

SI Units and Metric System

The Système International d’Unités (SI) is the modern metric system used for scientific measurements.

• Mass: Kilogram (kg)

• Volume: Liter (L)

• Length: Meter (m)

• Prefixes: Change the meaning of units by powers of 10 (e.g., milli-, centi-, kilo-).

Unit Conversion and Dimensional Analysis

Unit conversion uses equivalencies and conversion factors to change one unit to another.

• Example: $1 \text{dL} = 0.1 \text{L}$

• Dimensional Analysis Steps:

  1. Determine desired units.

  2. Establish given information.

  3. Choose appropriate conversion factors.

  4. Solve the problem.

Significant Figures

Significant figures reflect the precision of a measurement. All nonzero digits are significant; zeros may or may not be, depending on their position.

• Rules:

  • Leading zeros are not significant.

  • Captive zeros (between nonzero digits) are significant.

  • Trailing zeros are significant only if there is a decimal point.

• Exact Numbers: Defined values (e.g., 1 ft = 12 in) have infinite significant figures.

Calculations and Rounding

• Addition/Subtraction: Result matches the least number of decimal places.

• Multiplication/Division: Result matches the least number of significant digits.

• Rounding: If the digit to be dropped is 5 or greater, increase the last retained digit by 1.

Scientific Notation

Scientific notation expresses numbers as a coefficient times a power of ten: $C \times 10^n$.

• Example: $560,000 = 5.6 \times 10^5$

• Only significant figures are shown in the coefficient.

Percent Calculations

Percent (%) expresses a part out of 100. It is calculated as:

• $\text{Percent} = \frac{\text{Part}}{\text{Whole}} \times 100$

• Application: Used in nutrition labeling, medication dosing, and solution concentrations.

Properties of Matter

Mass vs. Weight

Mass is the amount of material in an object, measured in grams (g). Weight is the force of gravity on an object and can vary with location.

• On Earth: Mass and weight are numerically similar.

• On Mars: Weight is less due to lower gravity, but mass remains the same.

Volume

Volume is the three-dimensional space occupied by matter, commonly measured in liters (L) or milliliters (mL).

• 1 mL = 1 cm3

• 1 tablespoon = 15 mL

Density and Specific Gravity

Density ($d$) is the ratio of mass to volume:

• $d = \frac{m}{V}$

• Example: Water has a density of $1.00 \text{g/mL}$ at room temperature.

• Specific Gravity: Ratio of the density of a sample to the density of water (unitless).

• $\text{Specific gravity} = \frac{\text{Density of sample}}{\text{Density of water}}$

Temperature Scales

Temperature measures the hotness or coldness of a substance. Common scales are Fahrenheit (°F), Celsius (°C), and Kelvin (K).

• $K = °C + 273$

• $°C = (°F - 32) \times \frac{5}{9}$

• $°F = (°C \times \frac{9}{5}) + 32$

Heat and Specific Heat

Heat is kinetic energy transferred from a warmer to a cooler body. Specific heat is the amount of heat needed to raise the temperature of 1 g of a substance by 1°C.

• $\text{Specific heat (SH)} = \frac{\text{heat}}{\text{mass} \times \Delta T}$

• Water: High specific heat; metals: low specific heat.

States of Matter

Matter exists in three common states: solid, liquid, and gas.

State	Shape	Volume	Particle Arrangement	Energy
Solid	Definite	Definite	Orderly, tightly packed	Lowest
Liquid	Indefinite	Definite	Less orderly, moving freely	Intermediate
Gas	Indefinite	Indefinite	No order, far apart	Highest

Measuring Matter in Health Care

Accuracy and Precision

Accuracy refers to how close a measurement is to the true value; precision refers to how close repeated measurements are to each other.

• Best Practice: Take multiple measurements and average them for accuracy and precision.

Dosage Calculations

Dosage calculations require careful unit conversions and consideration of patient weight.

• Steps:

  1. Determine units for the final answer.

  2. Identify given information.

  3. Choose conversion factors to cancel units.

  4. Set up and solve the equation.

• Example: For a 140 lb patient needing 28 mg/kg: $140 \text{lb} \div 2.2 \text{kg/lb} = 63.6 \text{kg}$; $63.6 \text{kg} \times 28 \text{mg/kg} = 1780.8 \text{mg}$

Units in Health Care

• Common Units: mg, g, mL, dL, mmol, mEq, lb, kg

• Drop Factor: gtt/mL (20 drops per mL, varies by IV tubing)

Percent in Health Applications

• Percent Active Ingredient: Used to calculate the mass of active drug in a tablet.

• Percent of Adult Dose: Used for pediatric dosing.

• Percent Daily Value: Used in nutrition labeling.

Summary Table: States of Matter

State	Shape	Volume	Compressibility	Particle Attraction
Solid	Definite	Definite	Nearly incompressible	Strongest
Liquid	Indefinite	Definite	Nearly incompressible	Intermediate
Gas	Indefinite	Indefinite	Compressible	Weakest

Key Formulas

• Density: $d = \frac{m}{V}$

• Specific Gravity: $\text{Specific gravity} = \frac{\text{Density of sample}}{\text{Density of water}}$

• Temperature Conversion: $K = °C + 273$; $°C = (°F - 32) \times \frac{5}{9}$; $°F = (°C \times \frac{9}{5}) + 32$

• Specific Heat: $\text{Specific heat (SH)} = \frac{\text{heat}}{\text{mass} \times \Delta T}$

• Percent: $\text{Percent} = \frac{\text{Part}}{\text{Whole}} \times 100$

Additional info: Some context and examples were inferred to ensure completeness and clarity for GOB Chemistry students.