IndietroGeneral Biology: Atoms, Chemical Bonds, and Water Properties
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Termini in questo insieme (26)
Matter is anything that takes up space and has mass, including organisms, rocks, and oceans.
Chemical elements are pure substances made of only one type of atom. An atom is the smallest unit of an element and matter.
Protons (+1 charge, 1 AMU, nucleus), Neutrons (0 charge, 1 AMU, nucleus), Electrons (−1 charge, 0 AMU, orbit nucleus).
Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur (CHNOPS), called bulk elements.
Atomic number is the number of protons in the nucleus, defining the element. Mass number is the sum of protons and neutrons in the nucleus.
Electron orbitals are 3D regions where electrons are found. Valence electrons are in the outermost shell and determine chemical reactivity.
Atoms are more stable and less reactive when their valence shells are fully occupied, typically 2 or 8 electrons.
Atoms of the same element with the same number of protons but different numbers of neutrons, resulting in different mass numbers.
Unstable isotopes that decay by emitting energy. Half-life is the time for half of the atoms to decay.
Attractive forces between atoms holding them together to form molecules and compounds.
Molecules contain two or more chemically bonded atoms. Compounds are molecules with two or more different elements.
Intramolecular bonds occur within the same molecule; intermolecular bonds occur between different molecules.
Covalent bonds share electrons between atoms. Types: non-polar (equal sharing) and polar (unequal sharing).
Measure of an atom's attraction for electrons, ranging from 0 to 4; affects bond polarity.
Formed by electrical attraction between oppositely charged ions (cations and anions) after electron transfer.
Weak interactions between a partially positive hydrogen atom and a highly electronegative atom (F, O, or N).
Water has polar covalent bonds and an asymmetrical shape, creating partial positive and negative charges.
Cohesion and adhesion, surface tension, high specific heat and heat of vaporization, and ice's lower density than liquid water.
Cohesion is water molecules sticking to each other; adhesion is water molecules sticking to other polar or charged surfaces.
Stable hydrogen bonds in ice create a lattice that spaces molecules farther apart, making ice less dense than liquid water.
Specific heat is the heat needed to raise 1g of water by 1°C. Heat of vaporization is heat needed to convert 1g of liquid water to gas.
Water dissolves many solutes due to its polarity, forming hydration shells around ions and polar molecules.
Hydrophilic substances dissolve in water (polar/charged). Hydrophobic substances do not dissolve (non-polar).
Acids increase H⁺ concentration; Bases decrease H⁺ concentration by accepting H⁺ or releasing OH⁻.
Measures H⁺ concentration from 0 (acidic) to 14 (basic), with 7 being neutral. pH is logarithmic and inversely related to H⁺ concentration.
Substances that resist pH changes by absorbing or releasing H⁺, helping organisms maintain homeostasis.