Ch.2 Achieve Flashcards
(24 cards)
What kind of bond joins hydrogen to oxygen in a water molecule?
Polar covalent bond
The hydrogen atoms in a water molecule have a ______ charge while the oxygen atom has a ______ charge.
partial positive; partial negative
In an ice crystal, any single water molecule typically forms hydrogen bonds with how many other water molecules?
4
If present in a molecule, which atom is least likely to participate in hydrogen bonds with water?
Carbon
What else is necessary in order for a hydrogen atom in a molecule to participate in a hydrogen bond?
It must be bonded to a more electronegative atom.
Why does ice float?
The crystal lattice forces a less dense arrangement of molecules.
Which component of an atom has the smallest mass?
Electron
Which statement is true regarding a polar molecule?
A polar molecule is hydrophilic and will dissolve in water.
The class of organic molecules defined by a physical property rather than a structure are the:
Lipids
For the first three rows of the periodic table, elements in the same row have the same number and type of:
electron orbitals.
Example of a hydrogen bond?
the bond that forms between a hydrogen atom in one water molecule and an oxygen atom in another water molecule
An organic molecule must contain which element?
Carbon
Imagine that you have a simplified structural diagram of an organic molecule, as shown, with no letters included. What can you deduce?
The molecule contains only carbon and hydrogen.
The covalent linkage joining two amino acids together is referred to as a(n) _____ bond.
Peptide
Which nucleotide could base pair with a pyrimidine?
Adenine
Water is able to dissolve many compounds as a result of which of the answer options?
the fact that water molecules are polar
Which property of water is primarily responsible for the ability of trees to draw water up from the roots to the leaves?
cohesion
Which statement about carbon is correct?
Carbon-carbon single bonds allow for free rotation around the bond; carbon–carbon double bonds do not allow for free rotation around the bond.
Where is the highest-energy electron found in an atom of hydrogen?
in the spherical orbital closest to the nucleus
A woman’s doctor tells her to gargle with saltwater. She stirs a tablespoon of salt into a cup of warm water and watches the salt dissolve. Why does the salt dissolve in water?
The partial positive charges on hydrogen atoms in water molecules are attracted to chlorine ions, and the partial negative charges on oxygen atoms in water molecules are attracted to sodium ions.
The designation of a magnesium ion as Mg2+ indicates an atom that has:
lost two electrons and is positively charged.
Nucleotides A and T pair in DNA double helix with three hydrogen bonds. Two hydrogen atoms that are covalently connected to nitrogen atoms are positively charged because:
Nitrogen atom’s electronegativity is higher than that of hydrogen atom.
In DNA molecules, complementary base pairs always include one purine nucleotide and one pyrimidine nucleotide. Suppose you analyzed the DNA from some bacterial cells and you found that 16% of the nucleotides are adenine nucleotides.
What are the percentages of the other nucleotides in the bacterial DNA
16% thymine, 34% guanine, 34% cytosine
You are given two jars filled with fat, which is solid at room temperature. Chemical analyses of the contents of the jars show that the fat in both jars consists of saturated fat. The fat in the first jar became liquid when you raised its temperature to 37oC. On the other hand, the fat in the second jar was still solid at 37oC.
The fat in the second jar contains more fatty acids with longer hydrocarbon chains.
