Chp1 Matter and Measurement

Chemistry Overview

• Definition: Chemistry is the study of matter—its composition, properties, and transformations.

• Matter: Anything that has mass and occupies volume; exists naturally or is synthesized.

Categories of Matter

Living Things

• Plants, soil, water, protists, animals, air, fungus, bacteria.

Non-Living Things

• Light, minerals, sand, mud, water, rock.

States of Matter

• Solid:

  • Definite volume and maintains shape.

  • Particles lie close together in a regular 3D arrangement.

• Liquid:

  • Definite volume, no definite shape.

  • Particles are close together but can move around past each other.

• Gas:

  • No definite shape or volume.

  • Particles move randomly and are widely spaced.

• Plasma:

  • State at very high temperatures where atoms lose electrons.

Physical & Chemical Properties

• Physical Properties: Can be observed/measured without changing the composition of the material.

• Chemical Properties: Determine how a substance can be converted into another substance; involves chemical changes or reactions.

Examples of Changes

Physical Change

• Breaking glass, freezing a popsicle, slicing bread.

Chemical Change

• Spoiling milk, exploding fireworks, burning wood.

Classification of Matter

• Pure Substances:

  • Elements: Cannot be broken down (e.g., Hydrogen, Carbon, Iron).

  • Compounds: Formed by combining 2 or more elements (e.g., Water, Ammonia).

• Impure Substances (Mixtures):

  • Homogeneous Mixtures: Uniform composition throughout (e.g., salt solution).

  • Heterogeneous Mixtures: Varying composition (e.g., soil, wood).

Chemical Elements and Symbols

• Total of 118 elements, with 92 naturally occurring.

• Each has a unique symbol, examples include H (Hydrogen), O (Oxygen).

• Symbols create chemical formulas (e.g., H2O, C6H12O6).

Measurement Basics

• Measurement: Comprises a number and a unit; value without a unit is meaningless.

• Units of measure:

  • Mass: gram (g), kilogram (kg)

  • Length: meter (m)

  • Volume: liter (L)

  • Time: second (s)

Metric System

• Base units:

  • Length: meter (m)

  • Mass: kilogram (kg)

  • Volume: liter (L)

  • Electric Current: ampere (A)

  • Temperature: Kelvin (K)

Metric Prefixes

• Tera (T): 10^12

• Giga (G): 10^9

• Mega (M): 10^6

• Kilo (k): 10^3

• Centi (c): 10^-2

• Milli (m): 10^-3

• Micro (μ): 10^-6

• Nano (n): 10^-9

Measurement and Significant Figures

• Use significant figures and scientific notation to reflect precision.

• Rules for significant figures:

  • Middle zeros: significant.

  • Leading zeros: not significant.

  • Trailing zeros with decimal point: significant.

  • Trailing zeros without decimal point: may or may not be significant.

Scientific Notation

• Method to express large or small numbers:

  • E.g., 1,760,000,000,000 = 1.76 × 10^15.

• Rounding and calculations must respect significant figures.

Temperature and Heat

• Energy: Capacity to do work or supply heat; measured in calories (1 cal = 4.18 J).

• Temperature Conversions:

  • Celsius to Fahrenheit: F = (1.8 × C) + 32

  • Fahrenheit to Celsius: C = (F - 32) / 1.8

  • Kelvin to Celsius: K = C + 273.15.

Density

• Density: Ratio of mass to volume.

• Formula: Density = mass (g) / volume (mL or cm³).

Tables of Densities and Specific Heats

• Example substances with their densities:

  • Water: 1.0000 g/mL

  • Gold: 19.3 g/cm³

  • Ice: 0.917 g/cm³

Calculations and Problems

• Sample energy calculation for heating water:

  • Heat = mass × specific heat × temperature change.

• Example calculation for liquid volume based on density.

Conclusion

• Understanding chemistry involves mastering the properties, classification, measurement, and transformations of matter.