Properties and Classification of Matter & Atomic Structure Flashcards

Chemistry: The study of matter.
Matter: Anything that has mass and volume (takes up space), is made of atoms, and undergoes changes.
Energy Types:
- Kinetic Energy: Moving energy.
- Potential Energy: Stored energy.
Atom: The smallest particle of an element that still has the properties of that element.
Element: Pure substance made of only one kind of atom with a unique set of properties and symbol on the periodic table.
Key Statistics:
- There are $118$ known elements.
- $90\%$ of the universe is Hydrogen.

Pure Substance: Contains only one type of particle (can be solid, liquid, or gas).
- Element: $118$ options (e.g., $Fe$ , $Au$ , $O$ , $Br_2$ , $Na$ , $H_2$ , $O_2$ , $F_2$ ).
- Compound: Two or more different elements chemically combined in fixed proportions according to the Law of Definite Proportions (e.g., $H_2O$ , $NaCl$ , $C_6H_{12}O_6$ ).
Mixture: Contains two or more different types of particles (can be solid, liquid, or gas).
- Homogeneous Mixture
- Heterogeneous Mixture

Homogeneous Mixtures (Solutions):
- Appear to be one substance.
- Particles of different substances are evenly spread and cannot be visually separated (e.g., Vinegar, clean Air).
Heterogeneous Mixtures (Mechanical Mixtures):
- Particles of different substances remain in clumps.
- Components can be visually determined (e.g., Soil, Blood, Concrete, Beach sand).
Physical Properties: Describe the look or feel of a substance (e.g., mass, volume, color, texture, pH).
Physical Changes: Changes a physical property without altering chemical composition; no new substances form (e.g., phase changes, breaking glass, tearing paper, painting a house).
Chemical Properties: Ability to change into a different substance (e.g., flammability, tendency to oxidize, combustibility).
Chemical Changes: Rearrange bonds in a substance to form new substances (e.g., burning, cooking, reacting, neutralizing).

Types of Physical Properties:
- Intensive: Do not depend on sample size (e.g., color, boiling point, melting point).
- Extensive: Do depend on sample size (e.g., mass, volume).
Four Signs of a Chemical Change:
1. Sudden color change
2. Formation of a new gas (bubbles or smoke forms)
3. Formation of a precipitate (solid / PPT)
4. Release or absorption of energy
Law of Conservation of Matter: Matter, mass, and atoms are neither created nor destroyed in a chemical reaction. Mass is conserved.

Law of Definite Proportions (Proust): A compound is always composed of a fixed proportion of elements by mass (e.g., table salt is $60.66\%$ Cl and $39.34\%$ Na).
Law of Multiple Proportions (Dalton): Mass ratios of elements in a compound are small whole numbers (e.g., CO with $1\,g$ C per $1.33\,g$ O vs. $CO_2$ with $1\,g$ C per $2.66\,g$ O yields a $1:2$ ratio).
Atomic History:
- Dalton (1803): Proposed the "billiard ball model"—solid, smallest whole particle spheres in everything.
- Bohr (1922): Developed the planetary model with a positive central nucleus and orbiting negative particles; won the Nobel Prize in 1922.
Quantum Model Contributors:
1. de Broglie: Developed the idea that electrons behave like a wave and a particle.
2. Shrodinger: Developed the Quantum Mechanical Model using his wave equation.
3. Heisenburg: Formulated the Uncertainty Principle (speed and position of electrons are uncertain), making Bohr's model irrelevant.
4. Chadwick: Discovered the neutron.
5. Enstien: Determined that light behaves like a wave and a particle.
6. Gell-Mann: Discovered quarks (smaller particles that make up protons and neutrons).

Scientific Shorthand: Each element is represented by a one- or two-letter chemical symbol (one capitalized letter plus one lower case letter).
Modern Atomic Theory: Atoms of the same element have the same atomic number (protons) but can have different masses.
Subatomic Particles:
- Proton ( $p^+$ ): Located in the nucleus; Positive charge; Mass = $1\,AMU$ ; unique to each element.
- Neutron ( $n^0$ ): Located in the nucleus; Neutral charge; Mass = $1\,AMU$ ; contributes to mass only.
- Electron ( $e^-$ ): Located in the electron cloud outside the nucleus; Negative charge; Mass = $1/1836\,AMU$ ; allows bonding and determines charge.
Atom Make-Up:
- Nucleus: Center of the atom containing protons and neutrons; contains all the mass.
- Electron Cloud: Region outside the nucleus containing electrons; contains all the volume.
- Quarks: Particles that make up protons and neutrons ( $3$ per proton or neutron).
Atomic Number ( $Z$ ): Number of protons in the nucleus of an element; periodic table is ordered by increasing atomic number.
Atomic Mass: Sum of all isotopes of a particular element (e.g., Oxygen = $15.999\,amu$ ); closest to the most common isotope.

Mass Number ( $A$ ): Sum of protons and neutrons in the nucleus ( $A = p^+ + n^0$ ).
Neutron Calculation: $\text{Mass Number} - \text{Atomic Number} = \text{Number of Neutrons}$ .
Isotopes: Atoms with the same number of protons (atomic number) but a different number of neutrons relative to other atoms of the same element.
Two Ways to Designate Isotopes:
1. Hyphen Notation: Name/symbol followed by mass number ( $X-A$ ).
2. Nuclear Symbol: $^{A}_{Z}\text{X}$ with net charge.
Types of Atomic Charge:
- Net Charge: Overall charge based on $p^+ : e^-$ ratio. Neutral when $p^+ = e^-$ ; becomes an ion when $p^+ \neq e^-$ .
- Example ( $Ag$ ): Net charge = $0$ (neutral).
- Example ( $Ag^+$ ): Net charge = $+1$ (lost $1\,e^-$ ).
- Nuclear Charge: Positive charge based on the nucleus (protons).
- Example ( $Ag$ ): Nuclear charge = $+47$ .
- Example ( $Ag^+$ ): Nuclear charge = $+47$ (always the same for an element).