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sep 18

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Termini in questo insieme (22)

  • What is matter?

    Matter is anything that occupies space and has mass.

    3 physical states: solid, liquid, gas

  • What is an element?

    An element is a substance that cannot be broken down into other substances by normal chemical means.

  • What is a compound?

    A compound is a substance consisting of two or more elements combined in a fixed ratio, with characteristics different from its elements.

  • Name the 'Big Six' elements that make up 99% of the matter in the human body.

    Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N), Phosphorus (P), and Calcium (Ca).

  • What are trace elements?

    Trace elements are elements required in very small amounts by organisms, such as boron, chromium, cobalt, copper, fluorine, iodine, iron, manganese, molybdenum, selenium, silicon, tin, vanadium, and zinc.

  • What are the three main subatomic particles of an atom?

    Protons (positive charge), electrons (negative charge), and neutrons (neutral charge).

  • What is the atomic number of an atom?

    The atomic number is the number of protons in an atom.

  • What is the mass number of an atom?

    The mass number is the sum of the number of protons and neutrons in the nucleus.

  • What is an isotope?

    Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.

  • What is a radioactive isotope?

    A radioactive isotope has an unstable nucleus that decays spontaneously, releasing particles and energy (radiation).

    C12 and C13 are stable meanwhile C14 is not

  • How are radioactive isotopes used in medicine?

    They act as radioactive tracers for imaging and treatment, such as radioactive iodine targeting thyroid cancer.

  • What determines an atom's chemical properties?

    The distribution of electrons, especially those in the outermost shell, determines an atom's chemical properties.

  • What is the valence shell?

    The valence shell is the outermost electron shell of an atom.

  • What are valence electrons?

    Valence electrons are the electrons found in the valence shell, involved in chemical bonding.

  • What are inert atoms?

    Inert atoms have complete outer electron shells and do not interact with other atoms.

  • What happens during a chemical reaction between atoms with incomplete outer shells?

    Atoms can give up, accept, or share electrons to complete their valence shells.

  • What is an ionic bond?

    An ionic bond is formed by the transfer of electrons from one atom to another.

  • What is a covalent bond?

    A covalent bond is formed by the sharing of electrons between atoms.

  • What is electronegativity?

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

  • What is the difference between nonpolar and polar covalent bonds?

    Nonpolar covalent bonds share electrons equally; polar covalent bonds share electrons unequally, causing partial charges.

  • how many components is most living things made of

    at least 3 or 4

  • how many elements and plants need

    humans 25

    plants 17