Introduction to Elements and Atoms

Observations of Substances

• Humans have observed different substances with different properties for thousands of years.
• Substances can reflect light, be different colors, and exist as solids, liquids, or gases.
• Observations of reactions between substances.

Examples of Substances

• Solid substances: Carbon (graphite), Lead, Gold.
• Air particles: Carbon, Oxygen, Nitrogen.
• Substances can change states (solid to liquid to gas) with temperature changes.

Question of the Smallest Unit

• Philosophical question: Is there a smallest unit of a substance that still retains its properties?
• Answer: Yes, the smallest unit is called an "atom."

Elements

• Elements are pure substances with specific properties.
• Examples: Carbon, Lead, Gold, Oxygen, Nitrogen.
• Water is not an element; it's made of Oxygen and Hydrogen.
• All elements are listed in the Periodic Table.

Atoms

• Atoms are the smallest unit of an element.
• Example: A carbon atom is the smallest unit that still retains the properties of carbon.
• Atoms are extremely small.

Scale of Atoms

• Example: Human hair is about 1 million carbon atoms wide.

Fundamental Particles of Atoms

• Atoms are made up of protons, neutrons, and electrons.
• Changes in the number of protons change the element.

Protons

• Define the element.
• Number of protons equals the atomic number (seen in the periodic table).

Neutrons

• Can change without changing the element.

Electrons

• Orbit or move around the nucleus.
• Number of electrons can change, affecting the element's charge.

Structure of Atoms

• Nucleus: Contains protons and neutrons.
• Electrons are around the nucleus due to the electromagnetic force.

Atomic Charge

• Protons are positively charged; electrons are negatively charged.
• Atoms are neutral if protons equal electrons.

Chemical Reactions and Electron Interaction

• Atoms react based on electron configuration.
• Electrons can be transferred between atoms, affecting charges and reactions.

Conclusion

• Atoms are fundamental building blocks.
• They are composed of even smaller particles (protons, neutrons, electrons).
• Understanding atoms helps in predicting chemical reactions and changes.