Unit 1 Study Guide: Atoms and the Periodic Table

Element Identification and Chemical Symbols

Learning Target 1.B requires identifying the chemical name or symbol of an element given one or the other for elements with atomic numbers $1$ through $36$, as well as specific additional elements with atomic numbers $47$, $50$, $53$, $54$, $56$, $74$, $78$, $79$, $80$, $82$, and $83$. Chemical symbols are standardized one- or two-letter abbreviations derived from element names.

Key elemental pairs include:

• Hydrogen, which has the chemical symbol $\text{H}$.
• Iron, which has the chemical symbol $\text{Fe}$.
• Calcium, which has the chemical symbol $\text{Ca}$.
• Sodium, which has the chemical symbol $\text{Na}$.

In addition to these specific examples, all elements corresponding to atomic numbers $1$ through $36$, alongside $47$, $50$, $53$, $54$, $56$, $74$, $78$, $79$, $80$, $82$, and $83$, must be thoroughly reviewed for complete mastery.

Rutherford Gold Foil Experiment and Atomic Structure

Learning Target 7.B focuses on interpreting the results of the Gold Foil experiment to establish the modern foundational understanding of atomic structure. The Gold Foil experiment was conducted by the scientist Ernest Rutherford.

The experimental procedure involved directing a stream of positively charged alpha particles at a thin sheet of gold foil to observe their interaction with the gold atoms.

The experimental data provided revolutionary insights into the internal structure of the atom. Rather than being a solid, uniform mass, the atom was shown to consist almost entirely of empty space. The experiment demonstrated that nearly all of an atom's mass and its entire positive charge are concentrated in a extremely dense central core termed the nucleus. Positively charged alpha particles were deflected only when passing directly near or colliding with this positively charged nucleus.

Subatomic Particles and Atomic Architecture

Learning Target 7.D encompasses identifying, naming, and labeling the three core subatomic particles—protons, neutrons, and electrons—by their names, electrical charges, mass values, and structural locations within the atom.

Protons are located inside the central nucleus of the atom. They carry a positive electrical charge and have a mass of $1\,\text{amu}$.

Neutrons are also located inside the nucleus alongside the protons. They carry a neutral electrical charge (no charge) and have a mass of $1\,\text{amu}$. Together, protons and neutrons form the nucleus and account for virtually all of the atom's total mass.

Electrons reside outside of the nucleus, orbiting in the electron cloud surrounding the central core. They carry a negative electrical charge and have negligible mass compared to protons and neutrons.