Cards (132)

    • What occurs between two non-metals in covalent bonding?
      Covalent bonding occurs between two non-metals.
    • What is involved in a covalent bond?
      A covalent bond involves the electrostatic attraction between nuclei of two atoms and the electrons of their outer shells.
    • How are electrons treated in covalent bonding?
      No electrons are transferred but only shared in covalent bonding.
    • What happens when a covalent bond is formed?
      When a covalent bond is formed, two atomic orbitals overlap and a molecular orbital is formed.
    • Why does covalent bonding occur?
      Covalent bonding happens because the electrons are more stable when attracted to two nuclei than when attracted to only one.
    • How is a covalent bond represented?
      A covalent bond is represented by a short straight line between the two atoms, such as H-H.
    • How should covalent bonds be regarded in terms of electron pairs?
      Covalent bonds should not be regarded as shared electron pairs in a fixed position; the electrons are in a state of constant motion and are best regarded as charge clouds.
    • What can non-metals do in terms of electrons?
      Non-metals are able to share pairs of electrons to form different types of covalent bonds.
    • What does sharing electrons in a covalent bond allow atoms to achieve?
      Sharing electrons in the covalent bond allows each of the 2 atoms to achieve an electron configuration similar to a noble gas.
    • What is the octet rule?
      The octet rule refers to the tendency of atoms to gain a valence shell with a total of 8 electrons.
    • What does it mean if a central atom can accommodate more or less than 8 electrons?
      Accommodating more than 8 electrons in the outer shell is known as ‘expanding the octet rule’, while accommodating less than 8 electrons means the central atom is ‘electron deficient’.
    • What are Lewis formulas?
      Lewis formulas are simplified electron shell diagrams that show pairs of electrons around atoms.
    • How can a pair of electrons be represented in Lewis formulas?
      A pair of electrons can be represented by dots, crosses, a combination of dots and crosses, or by a line.
    • Why is Cl–Cl not a Lewis formula?
      Cl–Cl is not a Lewis formula since it does not show all the electron pairs.
    • What are the steps for drawing Lewis formulas?
      Steps for drawing Lewis formulas include counting total valence electrons, drawing the skeletal structure, placing electron pairs in bonds, adding more pairs to complete octets, forming double/triple bonds if necessary, and checking total electrons.
    • What are the steps for drawing Lewis formulas?
      1. Count the total number of valence electrons.
      2. Draw the skeletal structure to show how many atoms are linked.
      3. Use a pair of crosses or dots to put an electron pair in each bond.
      4. Add more electron pairs to complete the octets around the atoms (except H which has 2 electrons).
      5. If there are not enough electrons to complete the octets, form double/triple bonds.
      6. Check the total number of electrons in the finished structure equals the total number of valence electrons.
    • What is the total number of valence electrons in CH4?
      8 valence electrons.
    • What is the total number of valence electrons in NH3?
      8 valence electrons.
    • What is the total number of valence electrons in H2O?
      8 valence electrons.
    • What is the total number of valence electrons in HCN?
      10 valence electrons.
    • What is the total number of valence electrons in CO2?
      16 valence electrons.
    • Which elements are exceptions to the octet rule?
      Exceptions to the octet rule include H, Li, Be, B, and Al.
    • What does the octet rule state for elements below atomic number 20?
      The octet rule states that atoms try to achieve 8 electrons in their valence shells to have the same electron configuration as a noble gas.
    • How does hydrogen achieve a stable arrangement?
      Hydrogen achieves a stable arrangement by gaining an electron to become 1s2^2, the same structure as the noble gas helium.
    • How does lithium achieve a stable arrangement?
      Lithium achieves stability by losing an electron and going from 1s2^22s1^1 to 1s2^2 to become a Li+^+ ion.
    • How does beryllium achieve stability?
      Beryllium has two valence electrons and forms stable compounds with just four electrons in the valence shell.
    • How do boron and aluminum achieve stability?
      Boron and aluminum have 3 valence electrons and can form stable compounds with only 6 valence electrons.
    • What are the examples of Lewis structures with incomplete octets?
      Examples of Lewis structures with incomplete octets include BeCl2_2 and BF3_3.
    • How many electrons are shared in a single covalent bond?
      2 electrons are shared in a single covalent bond.
    • How many electrons are shared in a double covalent bond?
      4 electrons are shared in a double covalent bond.
    • How many electrons are shared in a triple covalent bond?
      6 electrons are shared in a triple covalent bond.
    • What is bond energy?
      Bond energy is the energy required to break one mole of a particular covalent bond in the gaseous state.
    • What does a larger bond energy indicate?
      The larger the bond energy, the stronger the covalent bond is.
    • What is bond length?
      Bond length is the internuclear distance of two covalently bonded atoms.
    • How does bond length relate to the forces of attraction?
      The greater the forces of attraction between electrons and nuclei, the more the atoms are pulled closer to each other, decreasing bond length and increasing bond strength.
    • Which type of bonds are the shortest and strongest?
      Triple bonds are the shortest and strongest covalent bonds due to the large electron density between the nuclei of the two atoms.
    • What are coordinate bonds?
      Coordinate bonds are formed when one atom donates both electrons to an electron-deficient atom.
    • What is an example of a dative bond?
      An example of a dative bond is in an ammonium ion where nitrogen donates a lone pair to a hydrogen ion.
    • What does VSEPR theory explain?
      VSEPR theory explains how the arrangement of electron pairs around a central atom minimizes repulsion and determines molecular shape.
    • What are the basic rules of VSEPR theory?
      1. All electron pairs and lone pairs arrange themselves as far apart in space as possible.
      2. Lone pairs repel more strongly than bonding pairs.
      3. Multiple bonds behave like single bonds.
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