Unit 1 Science 10th Grade

Triangle of Chemistry

Provides three interconnected perspectives to understand chemistry and the world around us.

Macroscopic Perspective

What we observe with our senses (sight, touch, smell, hearing - but not taste in chemistry).

Symbolic Perspective

How we represent what we see or how we represent particles we cannot see, including pictures, diagrams, symbols, and equations.

Microscopic Perspective

What is happening with the particles that are too small for us to see, explaining observations made at the macroscopic level.

Interconnection of Perspectives

The microscopic particles explain what we see at the macroscopic level, while the symbolic representation connects the two.

Odor Neutralizing Scented Gel Beads - Macroscopic Observation

The scent of the gel beads is stronger when closer and weaker when farther away.

Odor Neutralizing Scented Gel Beads - Symbolic Representation

A drawing or diagram that visually represents the macroscopic observation.

Odor Neutralizing Scented Gel Beads - Microscopic Explanation

Scent particles themselves have a smell and enter the nose, more concentrated close to the jar and spread out as they move away.

Core Claims of Particle Theory

All matter is made of tiny particles; atoms of the same element are the same; attractive forces differ between particles; particles are always moving.

States of Matter - Solid

Particles have specific organization, close spacing, and vibrate in fixed positions.

States of Matter - Liquid

Particles have less organization, close spacing, and can move past each other.

States of Matter - Gas

Particles have no fixed organization, large spacing, and move rapidly and randomly.

Physical Change

Individual particles do not change during a change in the state of matter.

Evidence for Particle Movement

Observing how smells spread or the evaporation of liquids demonstrates particle movement.

Nature of a Chemical Reaction

Reactions are created by the behavior of atoms, ions, and molecules, explaining observable phenomena.

Particle Interaction in Reactions

Particles must touch each other to react.

Changes During a Chemical Reaction

The particles themselves change, leading to new substances.

Experimental Examples of Reactions

Combinations like Na₂CO₃ + HCl, Na₂CO₃ + Ca(NO₃)₂, and FeCl₃ + KSCN illustrate various reactions (oxidation, bubbles, etc).

Role of Water in Reactions

The role of water in facilitating reactions is a key consideration.

Evaporation

The process by which a liquid turns into a gas at temperatures below its boiling point.

Particle Level of Evaporation

During evaporation, liquid particles gain enough kinetic energy to escape the liquid phase and enter the gas phase.

Isopropyl Alcohol Evaporation Lab

Procedure to monitor temperature and mass change of isopropyl alcohol as it evaporates at room temperature.

Decrease in Temperature

Expected effect during evaporation as the liquid turns into gas.

Decrease in Mass

Observation confirming that the liquid is turning into a gas during evaporation.

Factors Affecting Evaporation Rate

Different liquids evaporate at different rates due to varying attractive forces between their particles.

Alkanes

Generally evaporate faster due to weaker intermolecular forces.

Alcohols

Evaporate at varying rates, typically slower than alkanes but faster than water, depending on their structure and intermolecular forces.

Water

Evaporates relatively slowly due to strong hydrogen bonding between its molecules.

Average Kinetic Energy

A measure of the average kinetic energy of the particles within a substance.

Temperature

A measure indicating faster-moving particles at higher temperatures and slower-moving particles at lower temperatures.

Absolute Zero

The theoretical temperature at which particles would have minimal kinetic energy.

Kinetic Molecular Theory (KMT)

A theory that explains the macroscopic properties of gases in terms of the motion of their constituent particles. Its principles apply to all states of matter.

Macroscopic

Pertaining to observations made with the unaided senses; visible to the naked eye. In chemistry, what we observe through sight, touch, smell, and hearing (but not taste).

Meniscus

The curve in the upper surface of a liquid in a container, produced in response to the surface tension of the liquid and the walls of the container. Measurements are typically read at the bottom of the meniscus.

Microscopic

Pertaining to phenomena at the atomic or molecular level, too small to be seen directly with the senses. It explains what is happening with particles.

Organic Compound

A chemical compound that contains carbon, usually bonded to hydrogen, and often other elements like oxygen, nitrogen, or sulfur.

Particle Nature of Matter

The fundamental concept that all matter is composed of tiny, discrete particles (atoms, molecules, ions) that are in constant motion.

Phase Change

A physical process in which a substance goes from one state of matter (solid, liquid, gas) to another. Individual particles do not change during a phase change.

States of Matter

The distinct forms that matter can take: solid, liquid, and gas (and plasma, not discussed in depth here), characterized by differences in particle organization, spacing, and movement.

Streak Test

An experimental procedure used to compare the evaporation rates of different liquids by observing how quickly streaks of them disappear.

Symbolic

The representation of chemical phenomena using pictures, diagrams, chemical symbols, and equations.