Chemistry-Bonding

In a nonpolar covalent bond, electrons are A)shared equally by two atoms B)shared unequally by two atoms C)located in a mobile "sea" shared by many atoms D)transferred from one atom to another

A) A nonpolar bonds mean that both atoms equally share one or more pairs of electrons. If the electronegativity between the two are .4 and under then it is a nonpolar bond

What type of chemical bond is formed when one atom donates an electron to another atom? A)Ionic B)Elemental Iconic C)Electronic D)Covalent

A) An ionic bond is a bond between a nonmetal and a metal. They have electronegativity differences above .4 therefore the metal will gain an electron and the nonmetal will lose or "donate" an electron

In which liquid is hydrogen bonding the strongest A)HF(l) B)H2(l) C)CH4(l) D)NH3(l)

A) Hydrogen bonds are attractions between a δ+ hydrogen on one molecule and a lone pair on a very electronegative atom (N, O or F) on another molecule.

The formation of a chemical bond between two atoms is A)exothermic and evolves energy B)exothermic and absorbs energy C)endothermic and evolves energy D)endothermic and absorbs energy

A) The formation of a chemical bond releases energy. Exothermic is the word that describes a process of releasing energy

Which compound contains a covalent bond with the greatest polarity? A)HF B)H2O C)BBr3 D)CCl4

A)HF Polarity can be measured by the difference of two atoms electronegativity. An atoms electronegativity can be found in Table S

Which is true about an atom that has 6 of 8 electrons in its outer shell? A)It will want to give up 2 electrons B)It will want to gain 2 electrons C)It will want to gain 6 electrons D)It is considered stable and will not react with other elements

B) An atom seeks to have a full valence shell. Since it already has 6 electrons it will look to gain two more electrons in order to have a full shell

A high electronegativity indicates a greater tendency for an element to A)gain protons B)gain electrons C)lose electrons D)lose protons

B) Electronegativity represents the tendency for an atom to attract electrons from another atom. A higher electronegativity is a greater tendency for an atom to gain electrons

Which type of substance is soft, has a low melting point, and is a poor conductor of heat and electricity? A)network solid B)molecular solid C)metallic solid D)ionic solid

B) Molecular solids form from a bond between two nonmetals forming a covalent bond. These typically have low melting points and are soft, nonconductors

If a covalent bond were to be formed between a nitrogen atom (electronegativity 3.0) and an oxygen atom (electronegativity 3.5), which of the following statements would best describe such a bond? A)Non-polar covalent B)Polar covalent where the oxygen atom carried the partial negative charge C)Polar covalent where the nitrogen atom carried the partial negative charge D)Polar covalent where the oxygen atom carried the partial positive charge

B) Since the oxygen atom is more electronegative, the electrons in the bond will be attracted to the O atom more strongly, creating positive and negative ends to the bond, i.e., a dipole. Since the oxygen atom is more electronegative, it will carry the partial negative charge.

Which of the following molecules would one expect to have a non-polar covalent bond? A)HCl B)F2 C)HF D)ClF

B) Since the two F atoms at either end of the covalent bond have the same electronegativities, the electrons will be perfectly evenly shared and the bond will be non-polar.

What type of chemical bonds share electrons between atoms? A)Ionic B)Electronic C)Covalent

C) Covalent bonds are bonds between two nonmetals. Since their electronegativities are very similar one nonmetal can't lose or gain an electron to another. This causes nonmetals to share a pair(s) of electrons

Which of the following is a halogen? A)O B)H C)Cl D)Na

C) Halogens are located in group 17 on the periodic table. Cl is in group 17

Which characteristic is a property of molecular substances? A)good heat conductivity B)good electrical conductivity C)low melting point D)high melting point

C) Molecular substances tend to be liquids and gases meaning that they have weak intermolecular forces. Therefore their boiling point would be low

The three dots in the Lewis dot diagram for boron indicate that it A)can bond with three other atoms. B)can only form triple covalent bonds. C)has three valence electrons. D)scores a 3 on Pauling's electronegativity scale.

C) The Lewis diagram for any atom shows only the valence (outer shell) electrons) of the atom. Boron atoms have three electrons in their outer shell, so will have three dots in their Lewis structures.

Hydrogen bonding is a type of A)Strong covalent bond B)Weak ionic bond C)Strong intermolecular force D)Weak intermolecular force

C) The hydrogen is often described as a strong electrostatic dipole-dipole interaction.

When sodium and fluorine combine to produce the compound NaF, the ions formed have the same electron configuration as atoms of A)neither argon nor neon B)both argon and neon C)neon, only D)argon, only

C) When Na and F combine they form an electron configuration of 2-8. Na electron configuration is 2-8-1 while F is 2-7, so when they form an ionic bond F will gain Na outermost electron to complete its valence shell due to having a higher negativity. Neon has an electron configuration of 2-8 but argon has 2-8-8

Which of the following has a complete valence shell? A)Be B)Cu C)Zn D)Xe

D) A complete valence shell requires an atom to have 8 electrons in their outermost shell. Xe like all noble gases do, has 8 electrons in its valence shell making it "complete"

Which atom in the ground state has a stable valence electron configuration? A)Al B)Na C)Si D)Ar

D) All three elements Al, Na, and Si have an incomplete valence shell while Ar has 8 valence electrons

Which statement is true of covalent bonds? A)No matter the element, there is the same bond length between neighboring atoms. B)Valence electrons must be shared equally between atoms in order to achieve stability. C)Covalent bonds form when the nuclei of two atoms attract each other. D)Atoms find the ideal separation distance where electrostatics forces are reduced to a minimum.

D) At various distances atoms experience different attractive and repulsive forces, ultimately finding the ideal separation distance where the electrostatic forces are reduced to a minimum.

Electrons orbit around the nucleus of an atom in layers. What are these layers called? A)Valences B)Covalents C)Bonds D)Shells E)Floors

D) Electrons take a circular orbit around its atoms. This circle like structure is referred to as a shell. The outermost shell is known as the atoms "valence shell"

Which of the following terms would best classify a sample of pure sodium chloride? A)An element B)A highly reactive metal C)A poisonous gas D)A compound

D) Sodium chloride is an example of a substance that has a fixed ratio of elements that are chemically bonded together to create in a single entity. Such substances are called compounds.

What feature of water molecules enables ionic substance to dissolve in water? A)The water molecules have a certain shape that allows them to surround the ions in solution. B)The water molecules react with the ions. C)The water molecules are sticky and can adhere to the ions. D)The water molecules are polar and are attracted to the positive and negative ions, surrounding them.

D) The polar bond in water (caused by the differences in electronegativity of the O and H atoms), are attracted to the oppositely charged ions and they surround the ions.

How many electrons are being shared between the two carbon atoms in the compound ethyne? Ethyne has the Lewis structure: H−C≡C−H A)1 B)2 C)3 D)6

D) Three lines between the carbon atoms in the Lewis structure represent three covalent bonds. Each covalent bond is a shared pair of electrons, hence there are six electrons being shared between the carbon atoms in ethyne.

What group of elements have a naturally full outer shell of electrons? A)Metals B)Transition metals C)Halogens D)Noble gases

D) The Noble gases located in group 18 have 8 electrons in their outermost shell. This can be seen in their electron configuration, for example, Ne has an electron configuration of 2-8. 8 electrons in the valence shell yields a naturally full outermost shell.

In the H-Cl bond, the two bonding electrons are A)closer to the hydrogen atom B)totally removed from the hydrogen atoms C)totally removed from the chlorine atom D)equidistant between the atoms E)closer to the chlorine atom

E) Cl has a higher electronegativity than H meaning that the shared electrons are pulled closer the Cl atom