Radioactive Decay: Alpha, Beta, Electron Capture
Alpha Decay
Radioactive nuclides with a very large atomic number (> 82) often decay with the emission of an alpha particle. By increasing the number of protons, Coulomb repulsion forces exceed the nuclear forces. Thus, the unstable nucleus emits a particle composed of two protons and two neutrons. The atomic number (Z = number of protons) decreases by two, and the mass number decreases by four. Q is the energy released in the process, the decay energy. Q is equivalent to the difference in mass
Read MoreUnderstanding Laws, States of Matter, and Chemical Reactions
A law is a brief statement of a general nature about regularities in nature observed experimentally. Boyle’s Law states that for a mass of gas at constant temperature, the product of the gas pressure exerted by the volume it occupies is constant.
States of Matter
- Gaseous State: It has no fixed shape or volume, is compressible, and flows easily.
- Liquid State: It adapts to the container, is difficult to compress, and flows.
- Solid State: It has its own rigid shape and volume and is hardly compressible.
Understanding Physics and Chemistry: Basic Principles
Physics and Chemistry: Basic Concepts
Physics
Part of the science of physical phenomena.
- Phenomenon: Any event under study.
- Physical Phenomena: Processes that do not alter the nature of the substances involved.
Chemistry
Part of the science of chemical phenomena.
- Chemical Phenomena: Processes that change the nature of the substances involved.
The Scientific Method
The scientific method consists of the following steps:
- Observation: Noting fixed natural events in order to reproduce them in the laboratory.
Water Treatment, Chemical Changes, and Alloys
Topic 5: Water Treatment Methods
Drinking water is not obtained by simple decanting. Water obtained from rivers and lakes is often unfit for human consumption. It’s usually murky, and if left to stand, waste deposits at the bottom.
Decanting (using a decanting funnel): Muddy water is carefully poured into another container to separate and extract the sediments. After decanting, the water may remain murky due to small suspended particles. These particles can be separated by filtration using filter
Read MoreMatter, Mixtures, and Material Properties Explained
Basic Concepts of Matter
Atom: Basic parts which consist of matter (protons, neutrons).
Molecule: Clusters of atoms that are in some substances (H2O).
Chemical element: Pure substances found in nature consist of countless atoms (gold, copper).
Compound: Substance formed by two or more elements with a constant rate and specific (H2O, CO2).
Pure substance: Elements with novel composition or properties (sugar, iron).
Mixtures and Separation Techniques
Mixture: Substances formed by several elements or compounds
Read MoreChemistry Fundamentals: History, Matter, and States
History of Chemistry
The first experiences of humans as chemists involved the use of fire to transform matter. Obtaining iron from ore and glass from sand are clear examples. Gradually, humans realized that other substances also have this power of transformation. Great efforts were devoted to finding a substance that transforms a metal into gold, which led to the creation of alchemy. The accumulation of alchemical experiences played a vital role in the future establishment of chemistry. Chemistry