MTEL General Science (64) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Independent variable

The factor the experimenter deliberately changes or manipulates in an investigation. Its effect is measured through the dependent variable while other conditions are held constant.

Control group

A comparison group that does not receive the experimental treatment. It provides a baseline for judging whether the manipulated variable actually caused an observed effect.

Accuracy versus precision

Accuracy is how close a measurement is to the true value; precision is how close repeated measurements are to each other. Systematic error reduces accuracy; random error reduces precision.

Percent error formula

Percent error equals the absolute difference between measured and accepted values, divided by the accepted value, then multiplied by 100. Reported as a nonnegative percentage.

Significant figures rule

Nonzero digits and zeros between them always count. Leading zeros never count. Trailing zeros count only with a decimal point. Multiplication uses the least significant figures; addition uses least decimal places.

Atomic number

The number of protons in an atom's nucleus, which uniquely identifies the element. In a neutral atom, it also equals the number of electrons.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons. They share chemical behavior but differ in mass number and stability.

Ionic versus covalent bonds

Ionic bonds transfer electrons between a metal and nonmetal, forming oppositely charged ions. Covalent bonds share electron pairs, usually between two nonmetals.

Mole concept

One mole equals 6.022 × 10²³ representative particles and has a mass in grams equal to the substance's molar mass. It bridges particle counts and measurable masses.

pH scale

pH equals the negative logarithm of hydrogen ion concentration. Values below 7 are acidic, 7 is neutral, and above 7 is basic; each unit represents a tenfold change.

Periodic table trends

Atomic radius decreases left to right and increases down a group. Ionization energy and electronegativity increase left to right and upward within a group.

Newton's second law

The net force on an object equals its mass times its acceleration (F = ma). Greater force or smaller mass produces greater acceleration.

Conservation of energy

In a closed system, total energy remains constant; energy transforms among kinetic, potential, thermal, and other forms but is never created or destroyed.

Kinetic versus potential energy

Kinetic energy is energy of motion, calculated as one-half mass times velocity squared. Gravitational potential energy depends on mass, gravity, and height (mgh).

Conservation of momentum

In an isolated system with no external net force, total momentum before a collision equals total momentum after. Momentum equals mass times velocity.

Ohm's law

Current through a conductor equals voltage divided by resistance (I = V/R). Electric power equals current times voltage (P = IV).

Wave equation

Wave speed equals frequency times wavelength (v = fλ). Frequency is determined by the source, while speed depends on the medium the wave travels through.

Transverse versus longitudinal waves

Transverse waves oscillate perpendicular to the direction of travel, like light. Longitudinal waves oscillate parallel to travel, like sound, forming compressions and rarefactions.

Electromagnetic spectrum order

From lowest to highest frequency: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma. Visible light runs from red (longest wavelength) to violet (shortest).

Refraction and Snell's law

Refraction is the bending of a wave as it changes speed crossing a boundary. Snell's law relates indices of refraction and angles: n₁ sin θ₁ = n₂ sin θ₂.

Convex versus concave lens

A convex lens converges light and can form real inverted images. A concave lens diverges light and forms only virtual, upright, reduced images.

Earth's internal layers

From surface inward: crust, mantle, liquid outer core, solid inner core. The metallic outer core's motion generates Earth's magnetic field.

Three rock types

Igneous rock forms from cooled magma or lava; sedimentary from compacted deposits; metamorphic from heat and pressure. The rock cycle links all three.

Cause of seasons

Seasons result from Earth's 23.5-degree axial tilt as it revolves around the Sun, changing the angle and duration of sunlight at each latitude.

Solar versus lunar eclipse

A solar eclipse occurs at new moon when the Moon blocks the Sun. A lunar eclipse occurs at full moon when Earth's shadow falls on the Moon.

Weathering versus erosion

Weathering breaks rock into smaller pieces in place, physically or chemically. Erosion transports the broken material, and deposition builds new landforms.

Cell theory

All living organisms are composed of one or more cells, cells are the basic unit of life, and new cells arise from existing cells.

Mitochondria versus chloroplasts

Mitochondria release energy from glucose through cellular respiration. Chloroplasts capture light energy and produce glucose through photosynthesis.

DNA base pairing

In double-stranded DNA, adenine pairs with thymine and guanine pairs with cytosine. Hydrogen bonds between pairs hold the two strands together.

Natural selection conditions

Natural selection requires heritable variation, differential survival or reproduction, and environmental pressure. Over generations, favorable traits increase in frequency within the population.

Ten percent rule

In an ecosystem, roughly ten percent of energy at one trophic level transfers to the next. The rest is lost mainly as heat, limiting food chain length.

Graph slope meaning

On a distance-time graph, slope is speed. On a velocity-time graph, slope is acceleration, and the area under the line is displacement.