Q: A photon of light has a wavelength of $500\ \mathrm{nm}$. What is the energy of this photon? (Use $h = 6.626 \times 10^{-34}\ \mathrm{J \cdot s}$, $c = 3.00 \times 10^8\ \mathrm{m/s}$)

$3.98 \times 10^{-19}\ \mathrm{J}$

Question 1

Which scientist is credited with discovering the nucleus through the gold foil experiment, fundamentally changing our understanding of atomic structure?

Accepted Answer

Ernest Rutherford

Question 2

An atom of carbon-14 has 6 protons, 6 electrons, and 8 neutrons. Which of the following statements is correct about carbon-14?

Accepted Answer

It is an isotope of carbon with a different mass number.

Question 3

Which of the following best describes the difference between a Bohr 'orbit' and a modern 'orbital'?

Accepted Answer

A Bohr orbit is a fixed path at a set distance from the nucleus, while an orbital is a region of space where there is a high probability of finding an electron.

Question 4

Which of the following elements is classified as an alkaline earth metal?

Accepted Answer

Magnesium (Mg)

Question 5

A sample contains two isotopes of chlorine: 75% $^{35}\mathrm{Cl}$ (atomic mass = 34.97 u) and 25% $^{37}\mathrm{Cl}$ (atomic mass = 36.97 u). What is the average atomic mass of chlorine in this sample?

Accepted Answer

$35.47\ \mathrm{u}$

Question 6

Which of the following best explains why elements in the same group of the periodic table have similar chemical properties?

Accepted Answer

They have the same number of valence electrons.

Question 7

Which of the following equations correctly relates the energy of a photon to its frequency?

Accepted Answer

$E = h 
u$

Question 8

A sodium atom ($Z=11$) loses one electron to form a $\mathrm{Na}^+$ ion. Which of the following statements is true?

Accepted Answer

The $\mathrm{Na}^+$ ion has 10 electrons.

Question 9

Which of the following trends is observed as you move from left to right across a period in the periodic table?

Accepted Answer

Atomic radius decreases, ionization energy increases.

Question 10

Which of the following ions is isoelectronic with neon ($\mathrm{Ne}$)?

Accepted Answer

$\mathrm{Na}^+$

Question 11

A photon of light has a wavelength of $500\ \mathrm{nm}$. What is the energy of this photon? (Use $h = 6.626 	imes 10^{-34}\ \mathrm{J \cdot s}$, $c = 3.00 	imes 10^8\ \mathrm{m/s}$)

Accepted Answer

$3.98 	imes 10^{-19}\ \mathrm{J}$

Question 12

Which of the following best describes the trend in ion size for an isoelectronic series as nuclear charge increases?

Accepted Answer

Ion size decreases as nuclear charge increases.

Question 13

Which of the following statements about metals and nonmetals is correct?

Accepted Answer

Nonmetals tend to gain electrons to form anions.

Question 14

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number ($l$)

Question 15

Which of the following electron configurations represents a neutral atom of sulfur ($Z=16$)?

Accepted Answer

$1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^4$

Question 16

Which of the following best explains why the first ionization energy of sodium is much lower than that of neon?

Accepted Answer

Sodium's outer electron is in a higher energy level, farther from the nucleus.

Question 17

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 18

Which of the following best describes the periodic trend for atomic radius as you move down a group?

Accepted Answer

Atomic radius increases due to additional electron shells.

Question 19

Which of the following is the correct order of increasing ionization energy for the elements: Na, Mg, Al?

Accepted Answer

Na < Mg < Al

Question 20

A student analyzes a sample and finds it contains only one type of atom, which cannot be broken down into simpler substances by chemical means. According to Dalton's atomic theory, what is this sample?

Accepted Answer

An element

Atoms, Elements, and Periodic Trends: Study Notes for Introductory Chemistry

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