Biochemistry___Lesson-2___Chapter 2.5 and 2.6 Flashcards

1
Q

What is the area around the nucleus of an atom that can hold 1 orbit / 2 electrons, or when farther away, 4 orbitals/ 8 electrons?

A

Electron shell

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2
Q

What is the outermost electron shell of an atom, which participates in chemical reactions only when it is not full?

A

Valence shell

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3
Q

What is the general name for an attraction that holds two atoms close together?

A

Chemical bond

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4
Q

What kind of chemical bond forms when an electron is transferred between atoms?

A

Ionic bond

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5
Q

What type of chemical bond forms when electrons are shared between atoms?

A

Covalent bond

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6
Q

What do we call a substance in which the atoms are held together by covalent bonds?

A

Molecule

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7
Q

What is the name of the attraction of an atomic nucleus for electrons?

A

Electronegativity

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8
Q

What type of chemical bond forms when electrons are shared equally between 2 atoms?

A

Nonpolar covalent bond

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9
Q

What type of chemical bond forms when electrons are shared unequally between 2 atoms?

A

Polar covalent bond

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10
Q

Draw a hydrogen atom (H) and label the valence shell.

A
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11
Q

Draw an oxygen atom (O) and label the valence shell.

A
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12
Q

Draw a nitrogen atom (N) and label the valence shell.

A
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13
Q

Draw a carbon atom (C) and label the valence shell.

A
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14
Q

Draw the structural formula and electron distribution diagram of hydrogen gas (H2).

A
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15
Q

Draw the structural formula and electron distribution diagram of oxygen gas (O2).

A
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16
Q

Draw the structural formula and electron distribution diagram of methane (CH4).

17
Q

Draw the structural formula and electron distribution diagram of water (H2O).

18
Q

How many electrons can be held in the first energy shell?

19
Q

How many electrons can be held in the second energy shell?

20
Q

How many electrons can be held in the third energy shell?

21
Q

How many electron shells do atoms in the first row of the periodic table have?

22
Q

How many electron shells do atoms in the second row of the periodic table have?

23
Q

What directly determines the chemical properties of an atom?

A

Valence electrons

24
Q

How many covalent bonds can a Hydrogen atom form?

25
How many covalent bonds can an Oxygen atom form?
2
26
How many covalent bonds can a Nitrogen atom form?
3
27
How many covalent bonds can a Carbon atom form?
4
28
What is the difference between a polar covalent bond and a nonpolar covalent bond?
Both share electrons, but the polar bond shares them unequally.
29
Explain the formation of a water molecule. Use all these phrases: 2 unpaired valence electrons, 1 unpaired valence electron, sharing, filled valence shell (8 electrons), filled valence shell (2 electrons), covalent bond.
A water molecule (H2O) is formed when an oxygen atom (2 unpaired valence electrons) fills its valence shell by sharing each unpaired electron with the unpaired electron of a hydrogen atom (1 unpaired valence electron). The result is oxygen with a filled valence shell (8 electrons) and 2 hydrogen atoms, each with a filled valence shell (2 electrons). The oxygen atom is sharing a pair of electrons with 2 different hydrogen atoms. The sharing causes the oxygen and hydrogen atoms to stay close together in what is called a covalent bond.
30
Describe the structure of a water molecule. Include partial charges in your drawing. Use all these phrases: covalent bond, not shared equally, electronegativity, polar covalent bond, slightly negative, slightly positive.
Oxygen forms 2 covalent bonds with 2 different hydrogen atoms. The electrons in the covalent bonds are not shared equally because oxygen has a greater electronegativity compared to hydrogen. The shared electrons in each covalent bond are thus closer to oxygen, forming a polar covalent bond. Because the electrons (which are negative) are closer to oxygen, the oxygen has a slightly negative charge, and the hydrogens have a slightly positive charge.