recall and basic understanding
state the ion charge of a proton, neutron, and electron
+, no charge, -
An atom has 17 protons, 18 neutrons, and 17 electrons. What are its atomic number and mass number?
it has 17 atomic number and 35 mass number
Write the full electron configuration of an atom with atomic number 11.
2, 8, 1
The first four ionisation energies of an element are 578, 1817, 2745, and 11577 kJ mol⁻¹. Between which two ionisation energies is there a large increase? What does this tell you about the number of outer-shell electrons?
There is a large increase between the 3rd and 4th ionisation energies. This means the atom has 3 outer-shell electrons.
An atom has 11 protons and 12 neutrons. Another atom has 11 protons and 14 neutrons. Are these atoms the same element? Explain your answer.
yes
Why is a neutron not affected by an electric field?
because it has no ion charge
Write the nuclide notation for an atom that has 12 protons and 13 neutrons.
12X25
Write the full electron configuration of an atom with atomic number 17.
2, 8, 7
Why is the second ionisation energy of sodium much higher than its first ionisation energy?
After one electron is removed, sodium has a stable electron configuration. The second electron must be removed from an inner shell, which is closer to the nucleus and harder to remove.
An atom has 2 electrons in its first shell, 8 electrons in its second shell, and 7 electrons in its third shell. Identify the element and write its electron configuration.
The element is chlorine (Cl). Its electron configuration is 1s22s22p63s23p5 or 2,8,7.
What is the difference between a shell, a subshell, and an orbital?
A shell is a main energy level. A subshell is part of a shell, such as s, p, or d. An orbital is a region where an electron is likely to be found.
Atom A has 8 protons and 8 neutrons. Atom B has 8 protons and 10 neutrons. Explain why these two atoms are isotopes.
they have the same number of protons
Write the electron configuration of an atom with atomic number 20 using shell notation.
1s2 2s2 2p6 3s2 3p6 4s2
What happens to atomic radius as you move from left to right across a period?
Atomic radius generally decreases from left to right across a period.
Element A has 2 electron shells, while Element B has 3 electron shells. Which element is likely to have the larger atomic radius? Explain your answer.
Element B has the larger atomic radius because it has more electron shells.
How many orbitals are there in an s subshell and in a p subshell?
s = 2 orbitals
p = 3 orbitals
An atom is written as 1939K. How many protons, neutrons, and electrons does it have?
19 protons, 20 neutrons, and 19 electrons
Write the full electron configuration of an atom with atomic number 26.
2, 8, 8, 8
What happens to atomic radius as you move down a group?
Atomic radius generally increases down a group because more electron shells are added.
Sodium and magnesium are in the same period. Which element has the higher first ionisation energy? Explain your answer.
Magnesium has the higher first ionisation energy because it has a greater nuclear charge while its outer electron is still in the same main shell.
how many electrons can each of the following subshells hold?
s = 2 electrons
p = 6 electrons
d = 10 electrons
Why can a p subshell contain a maximum of six electrons?
it has 3 orbitals and each contain 2 electrons
Write the electron configurations of the following ions:
a. Na⁺
b. Mg²⁺
c. Cl⁻
a. 2, 8
b. 2, 8
c. 2, 8, 8
Sodium (Z = 11) and chlorine (Z = 17) are in the same period. Which atom has a larger atomic radius? Explain your answer.
Sodium has a larger atomic radius than chlorine. Both atoms have electrons in the same number of shells, but chlorine has a greater nuclear charge, which pulls its electrons closer to the nucleus.
Element X has an electron configuration of 2,8,1, while Element Y has an electron configuration of 2,8,7. Which element has the larger atomic radius? Explain your answer.
Element X has the larger atomic radius. Both have three electron shells, but X has fewer protons, so its outer electrons are attracted less strongly to the nucleus.