Elements, The Periodic Table, and Atomic Structure: Week 2 Study Notes

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

4.1 Elements and Symbols

Definition and Importance of Elements

Elements are pure substances that cannot be broken down into simpler substances by chemical means. Each element is made up of only one kind of atom and is represented by a unique chemical symbol.

Element: A substance consisting of atoms with the same number of protons.
Chemical Symbol: A one- or two-letter abbreviation for an element, often derived from its English or Latin name.
Example: Sodium (Na), Carbon (C), Oxygen (O)

Chemical Symbols

Origin and Usage of Chemical Symbols

Chemical symbols are used universally to represent elements in chemical equations and formulas. Some symbols are derived from Latin names.

Examples from Latin: Fe (Ferrum for iron), Na (Natrium for sodium)
Application: Used in writing chemical reactions and formulas.

4.2 The Periodic Table

Organization and Structure

The periodic table arranges elements by increasing atomic number and groups elements with similar chemical properties into columns called groups or families.

Periods: Horizontal rows (numbered 1-7)
Groups: Vertical columns (numbered 1-18)
Group Names: Alkali metals (Group 1), Alkaline earth metals (Group 2), Halogens (Group 17), Noble gases (Group 18)

Table: Group Names in the Periodic Table

Group Number	Group Name
1	Alkali Metals
2	Alkaline Earth Metals
17	Halogens
18	Noble Gases

Metals, Nonmetals, and Metalloids

Classification and Properties

Elements are classified as metals, nonmetals, or metalloids based on their physical and chemical properties.

Metals: Good conductors of heat and electricity, malleable, ductile, shiny.
Nonmetals: Poor conductors, brittle, dull.
Metalloids: Properties intermediate between metals and nonmetals; semiconductors.

Table: Characteristics of Metals, Nonmetals, and Metalloids

Type	Properties
Metals	Shiny, malleable, ductile, good conductors
Nonmetals	Dull, brittle, poor conductors
Metalloids	Intermediate properties, semiconductors

4.3 The Atom

Atomic Theory and Structure

Atoms are the basic units of matter, composed of a nucleus containing protons and neutrons, surrounded by electrons.

Dalton's Atomic Theory: All matter is made of atoms; atoms of each element are identical; atoms combine in fixed ratios to form compounds.
Subatomic Particles: Protons (+), Neutrons (0), Electrons (-)
Structure: Nucleus (protons and neutrons), electron cloud (electrons)

Table: Subatomic Particles

Particle	Charge	Location	Relative Mass
Proton	+1	Nucleus	1
Neutron	0	Nucleus	1
Electron	-1	Electron cloud	~0

Atomic Models

Thomson's Plum Pudding Model: Electrons embedded in a sphere of positive charge.
Rutherford's Gold Foil Experiment: Atoms have a small, dense nucleus; most of the atom is empty space.

Atomic Number and Mass Number

Definitions and Calculations

The atomic number is the number of protons in an atom, which defines the element. The mass number is the sum of protons and neutrons in the nucleus.

Atomic Number ():
Mass Number ():
Atoms are neutral: Number of electrons equals number of protons.

Table: Comparison of Atoms of Different Elements

Element	Atomic Number	Mass Number	Protons	Neutrons	Electrons
Hydrogen	1	1	1	0	1
Carbon	6	12	6	6	6
Oxygen	8	16	8	8	8

4.5 Isotopes and Atomic Mass

Isotopes

Isotopes are atoms of the same element with different numbers of neutrons, resulting in different mass numbers.

Isotope: Same atomic number, different mass number.
Example: and

Atomic Mass

Atomic mass is the weighted average mass of all naturally occurring isotopes of an element.

Calculation:

Table: Atomic Symbols and Subatomic Particles

Protons	Neutrons	Electrons
6	6	6
6	8	6
12	12	12

Additional info:

Learning checks throughout the slides provide practice in identifying element groups, classifying elements, and calculating subatomic particles.
Health context: Some elements are essential for human health (e.g., Na, K, Ca, Fe).