Key Chemistry Definitions: Elements, Compounds, and Laws
Key Chemistry Definitions
- Pure Substance: Homogeneous matter that cannot be broken down through simple physicochemical processes.
- Element: A pure substance that cannot be broken down into simpler substances.
- Compound: A substance made of two or more different elements.
- Chemical Formula: Expresses the qualitative and quantitative composition of a given substance. The number in subscript form indicates the number of atoms.
- Ionic Species: A formula that takes a superscript indicating the net electrical
Understanding Nuclear Reactions, Fission, and Radioactivity
Energy Diagrams and Reaction Types
Graph Analysis:
- Product Energy: The product energy is represented by the middle value, approximately 30 kcal.
- Reagent Energy: The reagent energy is below 20 kcal.
- ΔH (Enthalpy Change): ΔH = Product Energy – Reagent Energy = 30 kcal – 20 kcal = 10 kcal. The reaction is exothermic, but the ΔH value is positive, which is unusual and may indicate an error in the data. Exothermic reactions typically have negative ΔH values.
- Activation Energy (Ea): The activation energy
Coordination Compounds: Roles in Biology, Chemistry, and Metallurgy
Coordination Compounds: Applications and Stability
9.27. Discuss briefly, giving an example in each case, the role of coordination compounds in:
(a) Biological systems
(b) Analytical chemistry
(c) Medicinal chemistry
(d) Extraction/metallurgy of metals
Answer:
(i) Coordination compounds are of great importance in biological systems. The pigment responsible for photosynthesis, chlorophyll, is a coordination compound of magnesium. Haemoglobin, the red pigment of blood which acts as an oxygen carrier,
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Understanding Sunset and Sunrise
Why is it assumed that the sun needs to be 6° below the horizon for it to get dark? Even when the sun is below the horizon, its light can still reach us because the Earth’s atmosphere acts like a giant prism, scattering the sun’s rays. This scattering causes the sky to continue to be illuminated even after the sun has set or before it has risen. The atmosphere also refracts the sunlight, bending the light around the curvature of the Earth. So, while the curvature
Read MoreChemical Bonds and Solutions: Understanding Intermolecular Forces
Chemical Bonds
The set of forces that hold atoms together when they form molecules and crystals, as well as the forces that hold molecules together when they are in a solid or liquid state.
Ionic Bond
An ionic bond occurs between elements that have a large difference in electronegativity, generally between a metal and a non-metal. This bond involves a total transfer of electrons from the less electronegative atom to the more electronegative atom, resulting in both atoms achieving a noble gas configuration.
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Chemical Bonds: An In-Depth Look
The density of materials is generally high, especially in transition metals due to their compact structures. Atoms with high atomic numbers and minimal gaps between them exhibit high intensity.
Covalent Bonds
A covalent bond is formed when two atoms share one or more pairs of electrons. The covalent valence of an element is its ability to form covalent bonds. For example, oxygen has a covalency of 2, as seen in water (H2O), where it forms two covalent bonds.
In covalent
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