Introduction to Chemistry: Matter, Measurement, and Scientific Method

Lecture 1: Chemistry and Our Lives

Overview

This section introduces the foundational concepts of chemistry, focusing on matter, its properties, and the methods used to study and measure it. Understanding these basics is essential for further study in General, Organic, and Biological (GOB) Chemistry.

Introduction to Chemistry

Definition and Scope

• Chemistry is the study of matter and its properties.

• Matter is anything that has mass and occupies space.

• Chemistry explores how substances interact, combine, and change to form new substances.

What is Matter?

Definition and Examples

• Matter is defined as anything that has mass and takes up space (volume).

• Examples: Air, water, rocks, living organisms.

• Non-examples: Light, heat, sound (these do not have mass or occupy space).

Chemicals

Definition and Everyday Examples

• A chemical is a substance that always has the same composition and properties wherever it is found.

• Examples: Table salt (sodium chloride), water (H2O), carbon dioxide (CO2).

• Many common materials and products are chemicals or mixtures of chemicals.

Scientific Method

Steps in Scientific Investigation

• Observation: Gathering information using the senses or instruments.

• Hypothesis: A tentative explanation or prediction that can be tested.

• Experiment: A controlled procedure to test the hypothesis.

• Model (Theory): A well-tested explanation that unifies a broad range of observations.

• Further Experiment: Additional testing to refine or challenge the model.

Qualitative and Quantitative Analysis

Types of Observations

• Qualitative: Describes qualities or characteristics (e.g., color, odor, texture).

• Quantitative: Involves measurements and numbers (e.g., mass, length, temperature).

Quantitative Measurements

Importance in Chemistry

• Quantitative measurements provide numerical data about properties of matter.

• Common properties measured: mass, length, volume, temperature.

SI Units

Standard Units of Measurement

• The SI (Système International d'Unités) is the standard system of measurement in science.

• SI units are based on seven base units, from which other units are derived.

Base SI Units

Quantity	Unit Name	Symbol
Mass	kilogram	kg
Length	meter	m
Time	second	s
Temperature	kelvin	K
Amount of substance	mole	mol
Electric current	ampere	A
Luminous intensity	candela	cd

Derived SI Units

Quantity	Derived Unit	Symbol
Area	square meter	m2
Volume	cubic meter	m3
Density	kilogram per cubic meter	kg/m3
Energy	joule	J
Pressure	pascal	Pa
Many more	—	—

Decimal Prefixes and Scientific (Exponential) Notation

Expressing Large and Small Numbers

• Scientific measurements often involve very large or very small numbers.

• Decimal prefixes (e.g., kilo-, milli-, micro-) are used to simplify these numbers.

• Scientific (exponential) notation expresses numbers as a product of a decimal part and a power of ten.

For example:

• Avogadro's number: $6.022 \times 10^{23}$

• Mass of an electron: $9.11 \times 10^{-31}$ kg

General form of scientific notation:

• $a \times 10^{n}$, where $1 \leq a < 10$ and $n$ is an integer.

Summary Table: SI Base Units and Prefixes

Prefix	Symbol	Multiplier
kilo	k	$10^{3}$
centi	c	$10^{-2}$
milli	m	$10^{-3}$
micro	\mu	$10^{-6}$
nano	n	$10^{-9}$
pico	p	$10^{-12}$
deci	d	$10^{-1}$
mega	M	$10^6$

Example: The length of a bacterium might be $2 \times 10^{-6}$ meters, or 2 micrometers ($2 \mu m$).

Additional info: Understanding SI units and scientific notation is essential for performing calculations and communicating results in chemistry.