Question

name:
____ 23. which of the following statements regarding dalton’s atomic theory is not currently
a. chemical reactions involve the rearrangement of atoms to make new compounds.
b. atoms of different elements are different; in particular, they have different
masses.
c. all elements are composed of atoms, which are indivisible and indestructible
particles.
d. compounds are formed by the joining of atoms of two or more elements.
____ 24. consider a neutral atom with 30 protons and 34 neutrons. the atomic number of the element is
a. 30
c. 34
b. 32
d. 64
____ 25. according to the periodic table, which of the following pairs of elements would most likely form a
covalent bond?
a. s and f
d. n and bi
b. li and br
e. mg and cl
c. ne and ar
____ 26. the diagram shows bohr model of the electron configuration around the chlorine nucleus. chlorine
has 17 protons.
diagram of chlorines bohr model
which of the following correctly completes the statement?
chlorine has ____ valence electrons, and the effective nuclear charge, ( z_{\text{eff}} ), for the chlorine
atom shown is ______.
a. 7; +7
c. 10; -7
b. 7; -7
d. 17; +7

Explanation:

1. Question 23: Dalton's original theory stated atoms are indivisible/indestructible, but we now know atoms are made of subatomic particles (protons, neutrons, electrons) and can be split in nuclear reactions. Options a, b, d are still valid modern restatements of his theory.
2. Question 24: Atomic number equals the number of protons in a neutral atom, which is given as 30.
3. Question 25: Covalent bonds form between two nonmetals when they share electrons. S (sulfur) and F (fluorine) are both nonmetals. Li/Br and Mg/Cl form ionic bonds, Ne/Ar are noble gases that do not bond readily, and N/Bi rarely form a stable covalent bond.
4. Question 26: Chlorine is in group 17, so it has 7 valence electrons. The effective nuclear charge for valence electrons matches the net positive charge they experience, equal to the group number, $+7$.

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Answer:

1. c. All elements are composed of atoms, which are indivisible and indestructible particles.
2. a. 30
3. a. S and F
4. a. 7; +7