Introductory Chemistry: Chapter 1 - Atoms and Elements

Practice flashcards covering Chapter 1 topics: chemistry, atomic structure, isotopes, and periodic table organization.

What is the study of chemistry?

The study of matter and the changes that matter undergoes.

What is matter?

Anything that has mass and occupies space.

What is mass in chemistry?

A measure of the amount of matter.

What are the key components of the scientific method described in the notes?

Observations, Law, Hypothesis, and Theory or Model.

Define an atom.

The smallest quantity of matter that still retains the properties of matter.

Define an element.

A substance that cannot be broken down into simpler substances by any means.

State Dalton's atomic theory (three core ideas).

Matter is made of atoms; all atoms of a given element are identical; atoms of one element differ from atoms of any other.

What is electric charge and how do charges interact?

Charge can be positive or negative; opposite charges attract; like charges repel; larger charges interact more strongly.

Name the three subatomic particles and their charges.

Electron (−), proton (+), neutron (neutral).

What did Thomson's cathode ray experiment reveal?

Atoms contain electrons and imply a positively charged center, leading to the plum-pudding model.

What did Rutherford's gold foil experiment reveal?

Nucleus exists; atoms have most mass in the nucleus; nucleus contains protons and neutrons; atom is mostly empty space.

What are the three subatomic particles in the Nuclear Atomic Model?

Electrons (−), protons (+), neutrons (no charge).

What conclusions about charge neutrality did these experiments support?

Atoms are neutral overall; equal numbers of electrons and protons; neutrons vary.

Define atomic number Z.

The number of protons in an atom; identifies the element.

Define mass number A.

Total number of protons and neutrons in the nucleus.

How is an isotope denoted?

With the symbol X and superscript A and subscript Z: ^A_Z X.

What are the isotopes of hydrogen and their neutron counts?

Protium: 0 neutrons; Deuterium: 1 neutron; Tritium: 2 neutrons (all have 1 proton).

What is an atomic mass unit (amu)?

One-twelfth the mass of a carbon-12 atom; used to express atomic masses.

How is average atomic mass determined?

As a weighted average based on the percent abundance of each isotope.

What elements are the most abundant in the human body (about 99% of mass)?

Hydrogen, Carbon, Nitrogen, Oxygen, Calcium, Phosphorus.

What are groups and periods in the periodic table?

Groups are vertical columns; periods are horizontal rows.

Name the major groupings: alkali metals, alkaline earth metals, chalcogens, halogens, and noble gases.

Alkali metals = Group 1; alkaline earth metals = Group 2; chalcogens = Group 16; halogens = Group 17; noble gases = Group 18.

What is the zigzag line on the periodic table used for?

It separates metals from nonmetals; metalloids lie along the line.

How is element identity related to atomic number?

The atomic number (Z) equals the number of protons and defines the element.

Which element has atomic number 16 and what is its symbol?

Sulfur (S).