GEORGE BROWN College CHEM1046 Week Two - Atomic Structure, The Periodic Table, and Chemical Formulas

Study questions cover atomic structure, the periodic table, isotopes, chemical formulas, ions, and electrolytes based on the provided notes.

What is the term for the primary substance from which all matter is made?

Element

How many elements are known to exist, and how are they categorized?

118 total; 92 naturally occurring and the rest synthetic

What is the basic unit of matter?

Atom

Where are protons and neutrons located within an atom, and where do electrons go?

Protons and neutrons are in the nucleus; electrons orbit around the nucleus in electron shells

Name the three primary sub-particles of an atom.

Protons, neutrons, and electrons

Which sub-particle has a large mass and a positive charge?

Proton

Which sub-particle has a large mass and no charge?

Neutron

Which sub-particle has a small mass and a negative charge?

Electron

For hydrogen, how many protons, neutrons, and electrons are there?

1 proton, 0 neutrons, 1 electron (1p, 0n, 1e)

For helium, how many protons, neutrons, and electrons are there?

2 protons, 2 neutrons, 2 electrons (2p, 2n, 2e)

For lithium, how many protons, neutrons, and electrons are there?

3 protons, 4 neutrons, 3 electrons (3p, 4n, 3e)

Where is the heaviest concentration of sub-particles located in an atom?

In the nucleus (protons and neutrons)

What determines the unique properties of an element?

The different numbers of protons, neutrons, and electrons (sub-particles), especially protons

How is the periodic table organized, and what increase does it show?

Organized in groups; shows an increase in atomic number

What is an atomic symbol?

A one- or two-letter symbol; second letter is lowercase if two elements share the same first letter

Give examples of atomic symbols and their origins.

Hydrogen = H; Oxygen = O; Carbon = C; Calcium = Ca; Copper = Cu; Iron = Fe (from ferrum); Sodium = Na (from natrium)

What is atomic mass (mass number) and how is it written?

The mass number; written as A; a whole number (protons + neutrons)

What is atomic number, and what does it represent?

Atomic number Z; equals the number of protons; for a neutral atom, also equals the number of electrons

What happens when you put it all together: atomic number, atomic mass, protons, neutrons, and electrons?

Atomic number = # of protons (and electrons in a neutral atom); Atomic mass = protons + neutrons

How many protons, neutrons, and electrons does potassium (K) have in its first four shells as an example?

1st shell: 2; 2nd shell: 8; 3rd shell: 9; 4th shell: 0 (K has 3 shells in total in the example)

What is the outermost shell called, and what are its electrons called?

Valence shell; valence electrons

What rule describes why atoms seek full outer shells, typically 2 in the first shell and 8 in others?

The octet rule (two in the first shell, eight in the others)

What is an atom with a complete valence shell called, and what is the alternate common name for such atoms?

Inert (noble gas); chemically inactive; inactive/inert atom

What is an atom with an incomplete valence shell called?

Chemically active (reactive) atom

What pattern exists in the periodic table regarding valence electrons and shells?

Vertical groups indicate the number of electrons in the outermost shell; horizontal periods indicate the total number of electron shells

How many electron shells does lithium (Li) have and how are its electrons distributed?

Two shells: 2 in the first shell, 1 in the second shell

What are the typical valence electron counts for boron (B), oxygen (O), and fluorine (F)?

B: 3; O: 6; F: 7

What is an isotope in simple terms?

An element with the same number of protons (and electrons) but a different number of neutrons

Do isotopes behave differently chemically? Why or why not?

No; isotopes have the same electron configuration, so they react chemically in the same way

How is isotope notation written, and what determines the most abundant natural form?

Element name followed by mass number; the most abundant natural isotope is used to determine the natural atomic mass; the periodic table shows a weighted average (decimal) due to multiple isotopes

What are carbon isotopes 12C, 13C, and 14C in terms of protons and neutrons?

All have 6 protons; 12C has 6 neutrons; 13C has 7 neutrons; 14C has 8 neutrons

How many neutrons do magnesium isotopes have (Mg-24, Mg-25, Mg-26)?

Mg-24 has 12 neutrons; Mg-25 has 13 neutrons; Mg-26 has 14 neutrons

What is a radioisotope and what is the decay process called?

A radioactive isotope that decays to a more stable form; radioactive decay (emission of energy/particles)

What are common medical uses of radioisotopes?

Medical imaging (diagnostic tests) and treatment

What is a chemical formula?

The formula of a substance showing the types and numbers of atoms that make up the substance

How are subscripts and brackets used in chemical formulas?

Subscripts indicate the number of atoms; brackets group atoms and subscripts multiply outside the brackets (and any subscripts inside)

In the formula H2O, how many hydrogen and oxygen atoms are there?

Hydrogen: 2; Oxygen: 1

In the formula Mg(OH)2, how many Mg, O, and H atoms are present?

Mg: 1; O: 2; H: 2

In the formula C(NH2)4, how many C, N, and H atoms are present?

C: 1; N: 4; H: 8

What is a compound, and how does it differ from a molecule?

A substance formed when two or more elements chemically combine; all compounds are molecules, but not all molecules are compounds

What is a molecule, and what is a key caveat about molecules and compounds?

A molecule is two or more atoms bonded together; all compounds are molecules, but not all molecules are compounds

What is an ion, and what are the two main types?

An ion is a charged particle formed by loss or gain of electrons; cation (positive) and anion (negative)

Where do you place the charge on a chemical symbol or formula, and does the charge apply to the whole molecule?

Charge is shown as a superscript in the upper right; it applies to the whole molecule

What is an electrolyte, and why are electrolytes important?

A substance that dissolves into ions in water and conducts electricity; essential for body functions like nerve signaling and muscle activity

Which common substances are electrolytes and which are not, when dissolved in water?

Electrolytes: NaCl (Na+ and Cl-), NaOH (Na+ and OH-). Glucose (C6H12O6) is not an electrolyte; it does not form ions in solution

State the ion charges for the following: CH3+, SO4^2-, H+, Zn^2+, OH-

CH3+: C1, H3, charge +1; SO4^2-: S1, O4, charge -2; H+: H1, charge +1; Zn^2+: Zn1, charge +2; OH-: O1, H1, charge -1