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General Biology: Chemical Context of Life

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Termini in questo insieme (21)

  • What is an element?

    An element is a substance that cannot be broken down to other substances by chemical reactions.

  • What is a compound?

    A compound is a substance consisting of two or more elements in a fixed ratio.

  • What are essential elements?

    About 20–25% of the 92 natural elements are essential elements required for life.

  • What are trace elements?

    Trace elements are required by an organism in only minute quantities.

  • What subatomic particles make up an atom?

    Atoms consist of protons (positive charge), neutrons (no charge), and electrons (negative charge).

  • What defines an isotope?

    Isotopes are atoms of the same element that differ in the number of neutrons.

  • What is the atomic number?

    The atomic number is the number of protons in an atom's nucleus.

  • What are valence electrons?

    Valence electrons are electrons in the outermost shell that determine an atom's chemical behavior.

  • What is a covalent bond?

    A covalent bond is the sharing of a pair of valence electrons by two atoms.

  • Difference between single and double covalent bonds?

    A single bond shares one pair of electrons; a double bond shares two pairs.

  • What is electronegativity?

    Electronegativity is an atom's attraction for electrons in a covalent bond.

  • Difference between polar and nonpolar covalent bonds?

    Nonpolar covalent bonds share electrons equally; polar covalent bonds share electrons unequally due to differing electronegativities.

  • What is an ionic bond?

    An ionic bond forms when one atom strips electrons from another, creating charged ions.

  • Define cation and anion.

    A cation is a positively charged ion; an anion is a negatively charged ion.

  • What are salts?

    Salts are ionic compounds formed by ionic bonds, often found as crystals like sodium chloride.

  • What is a hydrogen bond?

    A hydrogen bond forms when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom.

  • What are Van der Waals interactions?

    Van der Waals interactions are weak attractions between molecules due to uneven electron distribution.

  • Why is molecular shape important?

    Molecular shape determines how biological molecules recognize and respond to one another.

  • What happens in a chemical reaction?

    Chemical reactions involve the making and breaking of chemical bonds to convert reactants into products.

  • What is chemical equilibrium?

    Chemical equilibrium is reached when forward and reverse reactions occur at the same rate, stabilizing reactant and product concentrations.

  • Example of an important chemical reaction in biology?

    Photosynthesis: Sunlight powers conversion of carbon dioxide and water into glucose and oxygen: \(6\ CO_2 + 6\ H_2O \rightarrow C_6H_{12}O_6 + 6\ O_2\)