Introduction to Chemistry: Basic Concepts and Principles

Posted on Aug 27, 2024 in Chemistry

Introduction to Chemistry

Types of Research

1. Applied Research

Applied research is generally carried out to solve a specific problem.

2. Basic Research

Basic research is carried out for the sake of increasing knowledge.

3. Technological Development

Technological development typically involves the production and use of products that improve our quality of life.

Matter and Its Properties

4. The Smallest Unit of Matter

The smallest unit of matter that retains the properties of that matter is an atom.

5. Definition of Element

An element is a pure substance that cannot be broken down into simpler, stable substances and is made of one type of atom.

6. Extensive Properties of Matter

Extensive properties are properties that depend on the amount of matter present, such as:

Volume
Mass
Amount of energy

7. Intensive Properties of Matter

Intensive properties are properties that don’t depend on the amount of matter present, such as:

Melting point
Boiling point
Density
Ability to conduct electricity
Ability to transfer energy as heat

8. Physical Changes of Matter

Physical changes are changes that don’t involve a change in the substance’s identity, such as:

Melting
Boiling
Grinding

9. Examples of Pure Substances

Pure substances are substances with a fixed composition, such as:

Elements (e.g., gold, oxygen)
Water (H₂O)
Sucrose (table sugar)
Other compounds

10. Examples of Homogeneous Mixtures

Homogeneous mixtures are mixtures that are uniform in composition (solutions), such as:

Sugar dissolved in water
Alcohol
Coffee
Mouthwash

11. Separating Matter in a Mixture

One way to separate the different kinds of matter in a mixture is through methods like:

Filtration
Vaporization
Centrifugation
Paper chromatography

Measurements and Calculations

12. Precision vs. Accuracy

If some measurements agree closely with each other but differ widely from the actual value, these measurements are precise but not accurate.

13. Direct Proportionality

If two quantities are directly proportional and one quantity increases by 10%, the other also increases by 10%.

14. Significant Figures in Calculations

In division and multiplication, the answer must have the same number of significant figures as the measurement with the fewest number of significant figures.

15. Units of Measurement

Here are some common units of measurement and the quantities they measure:

Meter (m): Distance
Kilogram (kg): Mass
Second (s): Time
Kelvin (K): Temperature
Mole (mol): Amount of substance
Ampere (A): Electric current
Candela (cd): Luminous intensity
Joule (J): Work

16. Qualitative vs. Quantitative Data

Qualitative data is descriptive and related to qualities, such as color, smell, and texture.

Quantitative data is numerical and related to quantities, such as mass, volume, and temperature.

17. Converting Measurements

(This section requires specific measurements to be converted. Please provide the measurements you want to convert.)

18. Rules for Significant Figures

Zeros between nonzero digits are significant.
Zeros in front of nonzero digits are not significant.
Zeros at the end of a number and to the right of a decimal point are significant.
Zeros at the end of a number are only significant if a decimal point follows.

Atomic Structure

19. Subatomic Particles

Particle	Charge	Mass Number	Location
Proton	Positive	1.673 x 10^-27 kg	Nucleus
Neutron	Neutral	1.675 x 10^-27 kg	Nucleus
Electron	Negative	9.109 x 10^-31 kg	Electron Cloud

20. Atomic Number

The atomic number of an element is the number of protons each atom of that element has.

21. Number of Electrons

(This section requires the element in question to determine the number of electrons.)

22. Conversions

(This section requires specific units and values for conversion. Please provide the necessary information.)

Electron Configurations

Electron-configuration notation: 1s¹
Noble-gas notation: [He] 2s² 2p⁶ = Neon
Orbital notation: (This section requires the element in question to draw the orbital notation.)

Periodic Trends

23. Atomic Radius

Atomic radius is one-half the distance between the nuclei of identical atoms that are bonded together. It generally:

Decreases across a period (due to increasing positive charge in the nucleus)
Increases down a group (due to increasing electron shells)

24. Electronegativity

Electronegativity is the measure of the ability of an atom to attract electrons from other atoms in a compound. It generally:

Increases across a period
Decreases down a group

25. Ionization Energy

Ionization energy is the energy required to remove an electron from a neutral atom. It generally:

Increases across a period
Decreases down a group

26. Element with Zero Electron Affinity

The element with an electron affinity of 0 kJ/mol is Argon (Ar), a noble gas.

27. Determining Period from Electron Configuration

The period of an element can be determined from its electron configuration by looking at the highest principal quantum number (n) present. For example:

[Ar] 3d⁴ 4s² is in period 4 (highest n is 4)
[Kr] 4d¹⁰ 5s² 5p⁶ is in period 5 (highest n is 5)

28. Metals vs. Nonmetals

Metals are typically malleable, ductile, have luster, and are good conductors of heat and electricity.

Nonmetals generally lack these properties.

29. Determining Oxidation Number

Rules for assigning oxidation numbers:

The sum of oxidation numbers in a neutral compound is zero.
The sum of oxidation numbers in a polyatomic ion equals the charge of the ion.
The oxidation number of a monatomic ion equals its charge.
Common oxidation numbers:
- H: +1 (except in metal hydrides where it’s -1)
- O: -2 (except in peroxides where it’s -1 and with F where it’s +2)
- F: -1

30. Writing Formulas for Compounds

To write formulas for compounds, use the following steps:

Write the symbols of the elements involved.
Determine the charges of each element based on their position in the periodic table or given information.
Balance the charges to create a neutral compound by using subscripts.

Finding Molecular Formulas

(This section requires specific data, such as percent composition or empirical formula and molar mass, to determine the molecular formula.)

31. Naming Compounds Using the Stock System

The Stock system involves naming the cation followed by a Roman numeral in parentheses indicating its charge, and then the anion with an -ide suffix. For example:

Cr³⁺ F^– = Chromium (III) Fluoride

32. Classifying Bonds

To classify bonds as ionic, covalent, or polar covalent, consider the electronegativity difference between the bonded atoms:

Ionic: Large electronegativity difference (typically > 1.7)
Polar Covalent: Moderate electronegativity difference (typically 0.3 to 1.7)
Nonpolar Covalent: Small electronegativity difference (typically < 0.3)

33. Drawing Lewis Structures

Lewis structures represent the arrangement of valence electrons in a molecule. To draw them, follow these steps:

Count the total number of valence electrons.
Arrange the atoms, usually with the least electronegative atom in the center.
Connect the atoms with single bonds.
Distribute the remaining electrons to satisfy the octet rule (or duet rule for hydrogen).
If necessary, form double or triple bonds to satisfy the octet rule for all atoms.

Introduction to Chemistry: Basic Concepts and Principles