science

Structure & Properties of Matter

Key Concepts of Matter

All matter is composed of atoms, which are the fundamental building blocks of all substances.

Molecules consist of two or more atoms bonded together, forming the basis of chemical compounds.

States of matter are categorized into solids (definite shape and volume), liquids (definite volume but no fixed shape), and gases (neither definite shape nor volume).

Physical changes, such as melting and boiling, do not result in the formation of new substances, while chemical changes, like burning and rusting, do create new substances.

Understanding the differences between physical and chemical changes is crucial for studying reactions and properties of materials.

Properties of Matter

Physical properties can be observed without changing the substance, such as color, density, and melting point.

Chemical properties describe a substance's ability to undergo changes that transform it into different substances, such as reactivity with acids or bases.

The arrangement and movement of atoms in different states of matter affect their physical properties, such as density and compressibility.

Chemical Reactions

Fundamentals of Chemical Reactions

A chemical reaction involves reactants transforming into products, represented by the equation: Reactants → Products.

Common signs of chemical reactions include color change, temperature change, and gas formation, indicating that a reaction has occurred.

The Law of Conservation of Mass states that in a closed system, atoms are neither created nor destroyed during a chemical reaction, only rearranged.

Types of Chemical Reactions

Synthesis reactions combine two or more reactants to form a single product (e.g., A + B → AB).

Decomposition reactions break down a compound into simpler substances (e.g., AB → A + B).

Single replacement and double replacement reactions involve the exchange of elements between compounds, showcasing the versatility of chemical interactions.

Forces & Motion

Newton’s Laws of Motion

Newton's First Law states that an object at rest stays at rest, and an object in motion stays in motion unless acted upon by an external force.

The Second Law, F = ma, quantifies the relationship between force, mass, and acceleration, illustrating how force affects motion.

Newton's Third Law asserts that for every action, there is an equal and opposite reaction, fundamental to understanding interactions between objects.

Concepts of Motion

Speed is defined as the distance traveled over time, while velocity includes direction, making it a vector quantity.

Understanding the difference between speed and velocity is crucial for analyzing motion in physics.

Real-world applications of these laws can be seen in sports, vehicle dynamics, and space exploration.

Energy

Types of Energy

Kinetic energy is the energy of motion, calculated using the formula KE = 1/2 mv², where m is mass and v is velocity.

Potential energy is stored energy based on an object's position or state, such as gravitational potential energy in elevated objects.

The Law of Conservation of Energy states that energy cannot be created or destroyed, only transformed from one form to another.

Energy Transformations

Energy can change forms, such as electrical energy converting to thermal energy in appliances, demonstrating practical applications of energy principles.

Examples of energy transformations include photosynthesis in plants (light energy to chemical energy) and hydroelectric power (potential energy to kinetic energy).

Understanding energy transformations is essential for studying systems in physics and environmental science.

Cells and Genetics

Cell Structure and Function

All living organisms are composed of cells, which are the basic units of life.

Prokaryotic cells lack a nucleus and are typically unicellular (e.g., bacteria), while eukaryotic cells have a nucleus and can be unicellular or multicellular (e.g., plants, animals).

Key organelles include the nucleus (control center), mitochondria (energy production), cell membrane (regulates entry/exit), cell wall (structure in plants), and chloroplasts (photosynthesis in plants).

Genetics and Heredity

DNA serves as the genetic code, containing instructions for the development and functioning of living organisms.

Genes are segments of DNA that determine specific traits, and Punnett Squares are tools used to predict inheritance patterns.

The distinction between dominant (represented by capital letters) and recessive alleles (lowercase letters) is fundamental in understanding genetic traits.

Evolution and Ecosystems

Evolution and Natural Selection

Natural selection is the process by which organisms with advantageous traits survive and reproduce, leading to evolutionary changes over time.

Fossils provide evidence of how species have changed and adapted throughout history, supporting the theory of evolution.

Adaptations are traits that enhance an organism's ability to survive in its environment, illustrating the dynamic nature of evolution.

Ecosystem Dynamics

Ecosystems consist of producers (plants), consumers (animals), and decomposers (fungi, bacteria), forming a complex web of interactions.

Food chains and webs illustrate the flow of energy and nutrients through an ecosystem, highlighting the interdependence of organisms.

Symbiotic relationships include mutualism (both benefit), commensalism (one benefits, one unaffected), and parasitism (one benefits, one harmed), showcasing ecological interactions.

Earth & Space Science

Earth’s Systems

The Earth is composed of layers: the crust, mantle, and core, each with distinct properties and functions.

Plate tectonics explain geological phenomena such as earthquakes, volcanoes, and mountain formation, emphasizing the dynamic nature of the Earth's surface.

The rock cycle describes the transformation of rocks through igneous, sedimentary, and metamorphic processes, while the water cycle illustrates the movement of water through evaporation, condensation, precipitation, and runoff.

Space Science

Gravity is the force that keeps planets in orbit around the Sun, playing a crucial role in the structure of the solar system.

The phases of the Moon are caused by its position relative to the Earth and Sun, affecting how we perceive its illumination from Earth.

Seasons result from the tilt of the Earth's axis, influencing climate and ecological patterns across the globe.

Engineering & Science Practices

Scientific Method

The scientific method involves a systematic approach: Ask a question, Research, Formulate a Hypothesis, Test, Analyze results, and Conclude.

Independent variables are intentionally changed to observe effects, while dependent variables are measured outcomes of the experiment.

Controlled variables are kept constant to ensure that the results are due to the independent variable alone.

Data Analysis and Engineering Design

Understanding how to interpret graphs, charts, and tables is essential for analyzing scientific data and drawing conclusions.

The engineering design process includes identifying a problem, brainstorming solutions, planning, building, testing, and improving designs based on criteria and constraints.

Evaluating solutions involves assessing their effectiveness and feasibility, which is critical in engineering and scientific research.