Week 2: Atomic Structure and Dalton's Theory

A set of Q&A flashcards covering atomic structure, Dalton's theory, Bohr model, mass units, valence electrons, atomic number, mass number, and related study tips.

What is an atom?

The smallest particle of an element that retains the characteristics of that element.

What is the charge and location of a proton in an atom?

Positive (+1) charge; located in the nucleus.

What is the charge and location of a neutron?

Neutral (0) charge; located in the nucleus.

What is the charge and location of an electron?

Negative (-1) charge; located outside the nucleus in electron shells around the nucleus.

According to Dalton's atomic theory, atoms are what kind of particles?

Tiny particles of matter.

According to Dalton, how do atoms of the same element compare to atoms of other elements?

Atoms of the same element are similar to each other and different from atoms of other elements.

What does Dalton's theory say about how atoms form compounds?

Atoms of two or more different elements combine to form compounds.

What does Dalton's theory say about atoms during a chemical reaction?

Atoms are rearranged to form new combinations.

What does Dalton's theory say about the creation or destruction of atoms in chemical reactions?

Atoms are never created or destroyed during a chemical reaction.

In Bohr's model, how do electrons move around the nucleus?

In defined, stable circular orbits (shells).

What labels the Bohr orbits and what is special about the n=1 orbit?

Orbits are labeled by the quantum number n; n=1 (K-shell) has the lowest energy.

How can electrons gain or lose energy in Bohr's model?

By jumping between allowed orbits, absorbing or emitting electromagnetic radiation.

How many electrons are allowed in each Bohr orbit?

A defined number of electrons per orbit ( varies by shell).

What is the atomic mass unit (amu) defined as?

One twelfth of the mass of the carbon-12 atom.

What are the approximate masses of a proton, a neutron, and an electron in amu?

Proton ≈ 1.007 amu; Neutron ≈ 1.008 amu; Electron ≈ 0.000549 amu.

Where are valence electrons located and what is their role?

Outermost shell; they are the highest-energy electrons and participate in bonding and reactions.

For representative elements (groups 1A–8A), what does the group number indicate?

The number of valence electrons.

What is mass number?

Total number of protons and neutrons in the nucleus; equals protons + neutrons; a whole number and not listed on the periodic table.

For a neutral atom, what is the relationship between the number of protons and electrons?

They are equal.

What does atomic number represent and where does it appear in the periodic table symbol?

The number of protons in an atom; unique to the element; appears above the symbol in the periodic table.

Which statement about Dalton's atomic theory is incorrect according to modern understanding?

Atoms are composed of protons, neutrons, and electrons.

Which subatomic particle is the smallest and lightest?

Electron.

What is true about the nucleus of sodium?

The nucleus has a charge of +11 (11 protons).