1A

Page 1: Atoms and Elements

• Study Design Dot Point: Understand definitions of elements, isotopes, ions, including:

  • Atomic number

  • Mass number

  • Number of protons, neutrons, and electrons

• Essential Prior Knowledge:

  • Existence of various types of atoms

  • Understanding of subatomic particles

Key Concepts

• Atoms: Fundamental unit of matter composed of protons, neutrons, and electrons.

Subatomic Particles

• Protons: Positively charged particles in the nucleus.

• Neutrons: Neutral particles found in the nucleus.

• Electrons: Negatively charged particles that surround the nucleus.

• Atomic Number (1.1.1.1): Unique number of protons in an atom, determines the element type.

• Mass Number (1.1.1.2): Total number of protons and neutrons, defines the mass of the atom.

• Isotopes (1.1.1.3): Variants of an element; atoms with the same atomic number but varying neutrons.

Key Terms and Definitions

• Atom: Smallest unit of matter.

• Atomic Number: Number of protons in an atom.

• Chemical Symbol: Abbreviation for an element.

• Compound: Two or more different atoms bonded together.

• Electron: Negatively charged outside the nucleus.

• Element: Pure substance of a single atom type.

• Ion: Atom that gained or lost electrons, acquiring a charge.

• Isotope: Same element with different neutron counts.

• Mass Number: Sum of protons and neutrons.

• Molecule: Non-metal atoms bonded by shared electrons.

• Neutron: Neutral particle in nucleus.

• Nucleus: Center of the atom with protons and neutrons.

• Periodic Table: Organized table of elements by atomic number.

• Proton: Positively charged particle in the nucleus.

• Subatomic Particle: Particles within an atom.

Page 2: The Periodic Table

• Periodic Table: Developed by Dmitri Mendeleev to organize elements.

• Chemical Symbols: Each element is represented by a unique symbol in the periodic table.

• Molecules and Compounds:

  • Molecules formed when atoms share electrons (e.g., O2).

  • Compounds formed from atoms of different elements (e.g., H2O).

Understanding Elements

• Atomic Number: Indicates number of protons (e.g., oxygen has an atomic number of 8).

• Unique Identity: Determined solely by protons; neutrons and electrons do not affect element identity.

• Formation of Ions: Charge changes occur when atoms gain or lose electrons, not affecting protons or neutrons.

Notation of Elements

• Format includes:

  • Atomic Number

  • Chemical Symbol

  • Relative atomic mass

Page 3: Mass Number

• Mass Number (1.1.1.2): Indicates total number of protons + neutrons.

• Calculation: Mass number = protons + neutrons.

  • Example: Oxygen atom with 8 protons and 8 neutrons has a mass number of 16.

• Electron Mass: Negligible in atomic mass calculations (approx. 1/1800 of proton/neutron).

Determining Neutrons

• From knowledge of atomic and mass number:

  • Formula: Neutrons = Mass number - Atomic number

  • Example: For calcium with a mass number of 40 and atomic number 20, Neutrons = 40 - 20 = 20.

Common Misconceptions

• Charge of Atoms: Neutral atoms have equal protons and electrons. Neutrons don't affect charge.

Page 4: Isotopes

• Isotopes (1.1.1.3): Same element with different mass numbers due to varying neutrons.

  • Examples include:

    • Protium (1H), Deuterium (2H), Tritium (3H).

• Representation of Isotopes: Mass number is a superscript to the left of the chemical symbol.

  • e.g., 1H, 2H, 3H for hydrogen isotopes.

• Stability: Many elements have stable isotopes (e.g., tin has 10 stable isotopes).

• Common Misconceptions: Atomic masses on the periodic table are averages of isotopes, not exact masses.

Page 5: Questions Overview

• Atoms: Basic building blocks of matter, essential for substance diversity.

Progress Questions

1. Neutrons in atom with atomic number 11 and mass number 23.

2. Determining mass number.

3. Isotope definitions.

4. True/False on isotopes' physical properties.

Summary of Theory

• Atomic Number: Number of protons.

• Mass Number: Sum of neutrons + protons.

• Isotopes: Same protons, different neutrons/mass.

Page 6: Additional Questions

• Questions test understanding of isotopes and atomic properties.

  • Example questions on isotopes, atomic numbers, and differences in mass number.

Topics

• Characteristics of isotopes.

• Changes during neutron release.

• Definitions and calculations involving atomic mass variables.

Page 7: Advanced Questions

• Experimentation and Mass Measurement: Importance of accurate measurements in distinguishing elements.

Discussion Points

1. Significance of calibration in experiments.

2. Validity of statements regarding element mass uniqueness.

Hints Summary

• Isotopes vary in neutrons.

• Mass number calculations include only protons and neutrons.

• Isotope characteristics maintain stability.