Atomic Structure & Subatomic Particles and Atomic Radius 1.1

A set of practice flashcards covering atomic structure, subatomic particles, ions, and atomic/ionic radii.

What are the three main subatomic particles in an atom and their charges?

Protons (+1), neutrons (0), and electrons (-1).

Where is the nucleus located and what does it contain?

The nucleus is in the center of the atom and contains protons and neutrons; it is positively charged.

What is the charge of protons and neutrons?

Protons have a +1 charge; neutrons have a 0 charge.

Where are electrons located and how do they relate to the nucleus?

Electrons orbit the nucleus in shells/energy levels; the atom is held together by the electrostatic attraction between the positively charged nucleus and negatively charged electrons.

What is the relative mass of protons, neutrons, and electrons?

Protons and neutrons each have a relative mass of 1; electrons have a relative mass of about 1/1836 (negligible).

What is the relative charge of protons, neutrons, and electrons?

Protons +1; neutrons 0; electrons -1.

In an electric field, how do electrons and protons deflect?

Electrons are deflected strongly toward the positive plate; protons are deflected toward the negative plate.

What happens to neutrons in an electric field?

Neutrons are not deflected because they are electrically neutral.

What is the value of the electron charge magnitude?

1.602 x 10^-19 coulombs (C).

What is the value of the proton charge magnitude?

+1.602 x 10^-19 C.

What does the atomic number Z represent?

The number of protons in the nucleus (and in a neutral atom, also the number of electrons).

What does the mass number A represent?

The total number of protons and neutrons in the nucleus (the nucleon number).

How do you calculate the number of neutrons N?

N = A − Z.

What is a nucleon?

A proton or a neutron.

In a neutral atom, how do the numbers of electrons and protons compare?

They are equal (electrons = protons).

What is an ion?

An atom that has gained or lost electrons, giving it a net electric charge.

What is a cation?

A positively charged ion formed when an atom loses electrons.

What is an anion?

A negatively charged ion formed when an atom gains electrons.

How many electrons does a Mg^2+ ion have if its atomic number is 12?

10 electrons.

If an element X has A = 63 and Z = 29, how many neutrons does it have?

N = A − Z = 63 − 29 = 34 neutrons.

How many protons does an element with Z = 12 have in any ion or neutral atom?

12 protons.

What is the general relationship between mass number A, protons Z, and neutrons N?

A = Z + N; N = A − Z; Z is the number of protons.

How many electrons does a neutral carbon atom (Z = 6) have?

6 electrons.

What is the definition of atomic radius?

Half the distance between the nuclei of two covalently bonded atoms of the same element.

What is the general trend of atomic radii across a period and down a group?

Across a period: generally decreases. Down a group: generally increases.

Why does atomic radius decrease across a period?

Increased nuclear charge (more protons) pulls electrons closer; shielding stays roughly the same because electrons are added to the same shell.

Why does atomic radius increase down a group?

More electron shells are added; shielding increases, reducing the pull of the nucleus on outer electrons.

What happens to ionic radii with increasing negative charge?

Ionic radii increase as negative charge increases (more electrons beyond the same nucleus).

What happens to ionic radii with increasing positive charge?

Ionic radii decrease as positive charge increases (fewer electrons, stronger attraction to the nucleus).

Why is there a sharp increase in atomic radius between a noble gas and the next period's alkali metal?

The next period adds a new principal quantum shell, increasing shielding and the atomic radius.

What is shielding in atomic structure?

Inner electron shells repel outer electrons, reducing the effective nuclear attraction felt by outer electrons.