IndietroGeneral Biology: Chemical Principles of Life
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Termini in questo insieme (26)
Matter is anything that has mass and takes up space.
An element is a substance that cannot be broken down by a chemical reaction and is made of one type of atom.
Compounds are made when two or more elements combine. They can have emergent properties that individual elements do not have alone.
Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N) are the Big 4 elements making up about 96% of living matter.
Trace elements are elements needed in very small amounts but are still essential for life, such as Calcium, Phosphorus, Potassium, and Sulfur.
Protons (+ charge) and neutrons (no charge) are in the nucleus; electrons (− charge) orbit outside the nucleus.
The atomic number is the number of protons in the nucleus and defines the element.
Atomic mass is the sum of protons and neutrons in the nucleus, measured in atomic mass units (amu).
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, resulting in different atomic masses.
A radioactive isotope is an unstable isotope that decays spontaneously, releasing particles and energy.
By measuring the ratio of parent to daughter isotopes and knowing the half-life, scientists estimate the age of rocks and fossils.
Potential energy of an electron depends on its distance from the nucleus; farther electrons have more potential energy.
An atom's chemical behavior is determined by its electron arrangement, especially the valence electrons in the outermost shell.
Valence electrons are electrons in the outermost shell that determine how an atom reacts and bonds with others.
A covalent bond forms when atoms share valence electrons to complete their outer shells.
Polar covalent bonds share electrons unequally due to different electronegativities; nonpolar covalent bonds share electrons equally.
Electronegativity is an atom's ability to attract shared electrons in a bond; higher electronegativity means stronger pull.
An ionic bond forms when one atom transfers electrons to another, creating oppositely charged ions that attract each other.
Cations are positively charged ions (lost electrons); anions are negatively charged ions (gained electrons).
A hydrogen bond is a weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.
Van der Waals interactions are weak, temporary attractions caused by uneven electron distribution creating temporary dipoles.
Covalent > Ionic > Hydrogen > Van der Waals
A molecule's shape determines how it interacts with other molecules and affects its function.
Chemical reactions break and form bonds, converting reactants into products and often involving energy changes.
Chemical equilibrium occurs when forward and reverse reactions happen at the same rate, keeping reactant and product concentrations constant.
6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂; sunlight energy converts carbon dioxide and water into glucose and oxygen.