Indietro
Problema 44a
Give molecular formulas corresponding to each of the following ball-and-stick molecular representations (red = O, gray = C, blue = N, ivory = H). In writing the formula, list the elements in alphabetical order. (a) Alanine (an amino acid)
Problema 44b
Give molecular formulas corresponding to each of the following ball-and-stick molecular representations (red = O, gray = C, blue = N, ivory = H). In writing the formula, list the elements in alphabetical order. (b) Ethylene glycol (automobile antifreeze)
Problema 44c
Give molecular formulas corresponding to each of the following ball-and-stick molecular representations (red = O, gray = C, blue = N, ivory = H). In writing the formula, list the elements in alphabetical order. (c) Acetic acid (vinegar)
- How many elements are presently known? About how many occur naturally?
Problema 46
Problema 46a
What are the molecular weights of the following pharmaceuticals? (a) C33H35FN2O5 (atorvastatin, lowers blood cholesterol)
- Which element accounts for roughly 75% of the observed mass of the universe? Which four elements make up 95% of the mass of the human body?
Problema 47
- Look at the alphabetical list of elements inside the front cover. What are the symbols for the following elements? (a) Gadolinium (used in color TV screens) (b) Germanium (used in semiconductors) (c) Technetium (used in biomedical imaging) (d) Arsenic (used in pesticides)
Problema 48
- Look at the alphabetical list of elements inside the front cover. What are the symbols for the following elements? (a) Cadmium (used in rechargeable Ni-cad batteries) (b) Iridium (used for hardening alloys) (c) Beryllium (used in the space shuttle) (d) Tungsten (used in light bulbs)
Problema 49
- Look at the alphabetical list of elements inside the front cover. Give the names corresponding to the following symbols: (a) Te (b) Re (c) Be (d) Ar (e) Pu
Problema 50
- Look at the alphabetical list of elements inside the front cover. Give the names corresponding to the following symbols: (a) B (b) Rh (c) Cf (d) Os (e) Ga
Problema 51
- What is wrong with each of the following statements? (a) The symbol for tin is Ti. (b) The symbol for manganese is Mg. (c) The symbol for potassium is Po. (d) The symbol for helium is HE.
Problema 52
- What is wrong with each of the following statements? (a) The symbol for carbon is ca. (b) The symbol for sodium is So. (c) The symbol for nitrogen is Ni. (d) The symbol for chlorine is Cr
Problema 53
Problema 54a
Examine Figure 2.2, A portion of Mendeleev's periodic table. (a) Which characteristic was used to organize the elements in the table?
Problema 54b
Examine Figure 2.2, A portion of Mendeleev's periodic table. How was Mendeleev able to predict with a high level of accuracy the properties of the undiscovered elements beneath Al and Si in the periodic table?
Problema 55f
Examine Figure 2.3, The periodic table. (f) Classify the following three elements as metals, nonmet-als, or semimetals: Mo, Br, Si.
Problema 55g
Examine Figure 2.3, The periodic table. (g) What is the symbol for the element located in period 3, group 4A?
- What are the rows called and what are the columns called in the periodic table?
Problema 56
- How many groups are there in the periodic table? How are they labeled?
Problema 57
- What common characteristics do elements within a group of the periodic table have?
Problema 58
- Where in the periodic table are the main-group elements found? Where are the transition metal groups found?
Problema 59
- Where in the periodic table are the metallic elements found? Where are the nonmetallic elements found?
Problema 60
- What is a semimetal, and where in the periodic table are semimetals found?
Problema 61
- Classify the following elements as metals, nonmetals, or semimetals: (a) Ti (b) Te (c) Se (d) Sc (e) Si
Problema 62
- Classify the following elements as metals, nonmetals, or semimetals: (a) Ar (b) Sb (c) Mo (d) Cl (e) N (f) Mg
Problema 63
- List several general properties of the following groups: (a) Alkali metals (b) Noble gases (c) Halogens
Problema 64
Problema 65a
(a) Without looking at a periodic table, list as many alkali metals as you can. (There are five common ones.)
Problema 65b
(b) Without looking at a periodic table, list as many alkaline earth metals as you can. (There are five common ones.)
- Without looking at a periodic table, list as many halogens as you can. (There are four common ones.)
Problema 66
- Without looking at a periodic table, list as many noble gases as you can. (There are six common ones.)
Problema 67
- At room temperature, a certain element is found to be a soft, silver-colored solid that reacts violently with water and is a good conductor of electricity. Is the element likely to be a metal, a nonmetal, or a semimetal?
Problema 68