Chem Exam 1 Flashcards

Everything learned 1/12-1/30; Chp 1 & 2

Avogadro's number

6.022 x 10^23, the number of molecules in one mole of a substance.

Elements

Pure substances that are the building blocks of matter.

Compounds

Chemical combinations of two or more elements that have specific properties.

Mixtures

Combinations of two or more pure substances that do not form chemical bonds.

Homogeneous mixture

A uniform mixture where composition is consistent throughout.

Heterogeneous mixture

A non-uniform mixture where components can be visually distinguished.

Chemical Properties

Characteristics that define how a substance can react chemically.

Physical Properties

Characteristics observable without changing the substance's identity. Ex - color, boiling point, shape, density

Significant Figures

Digits in a measurement that are meaningful and contribute to its precision.

Dimensional Analysis

A method to convert between units using conversion factors.

Dalton's Atomic Theory

Matter is made of indivisible particles (atoms) and atoms combine in whole-number ratios to form compounds.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons.

Ions

Atoms or molecules that have gained or lost one or more electrons, resulting in a positive or negative charge.

Atomic Mass

the total mass of protons, neutrons, and electrons in a single atom, measured in atomic mass units (u).

Periodic Table

A tabular arrangement of elements based on increasing atomic number, showing periodic trends.

matter

Anything that has mass and takes up space.

atom

The smallest unit of matter, consisting of protons, neutrons, and electrons

extensive property

A property that depends on the amount of matter in a sample, such as mass or volume.

aqueous solution

A solution in which water is the solvent, ex- tea.

Chemical change

involves breaking/forming of bonds & releasing/consuming energy.

energy

capacity to do work

kinetic energy

the energy of an object due to its motion

potential energy

the energy stored in an object due to its position or condition.

law

scientific observation that is always true

law of conservation of energy

states that energy cannot be created or destroyed, only transformed from one form to another.

qualitative

identity of a substance

quantitative

amount of substance that can be measured

Matter

Anything that has mass and takes up space.

Pure Substances

Materials that have a constant composition and consistent properties throughout.

Mixture

A combination of two or more substances that do not change during the mixing.

Homogeneous Mixture

A mixture that has a uniform composition throughout.

Heterogeneous Mixture

A mixture in which the composition is not uniform throughout.

Solution

A homogeneous mixture where one substance is dissolved in another.

Chemical Property

A property that becomes evident during or after a chemical reaction.

Intensive Property

Properties that do not depend on the amount of substance.

Chemical Reaction Notation

Represented as reactants → products.

International System of Units (SI)

The standard system of measurement used in science.

SI Prefix

A prefix used to indicate a multiple or fraction of a unit (e.g., kilo-, centi-).

Dimensional Analysis

A method using conversion factors to convert units.

Density

The mass per unit volume of a substance;

Celsius (°C)

A scale for measuring temperature based on the freezing and boiling points of water.

Fahrenheit (°F)

A temperature scale where the freezing point of water is 32 degrees.

Kelvin (K)

The SI unit of temperature, starting at absolute zero.

Significant Figures

Digits in a number that contribute to its accuracy.

Atomic Number

The number of protons in the nucleus of an atom.

Mass Number

The total number of protons and neutrons in an atom's nucleus.

Average Atomic Mass

isotope mass X fractional abundance of each isotope, add together for avg atomic mass.

Atomic Mass Unit (amu)

A unit of mass used to express atomic and molecular weights.

Law of Conservation of Mass

Matter cannot be created or destroyed in a chemical reaction.

Cation

A positively charged ion.

Anion

A negatively charged ion.

law of definite proportions

any compound is composed of definite proportions by mass of elements

Mass fractions in compound

mass fraction= (mass of element/mass of total compound)

law of multiple proportion s

When two elements form more than one compound, the mass ratios of the second element that combine with a fixed mass of the first element are in simple whole number ratios.

electron mass

9.10 × 10^-28 grams, lightest subatomic particle

Protons

positive charge (+1)

Electrons

negative charge (-1)

Neutrons

no charge (+0), MASS NUMBER-ATOMIC NUMBER

Atomic #

number of protons in an atom's nucleus, on bottom left of isotope

Atoms

Electrons around nucleus, protons and neutrons in nucleus.

Mass # (A)

number of protons + number of neutrons. number on top left of isotope

PT Group 1

Alaki Metals

PT Group 11

coinage metals

PT Group 18

noble gases (low reactivity)

PT Group 17

halogens (high reactivity)

PT Group 1,2 & 13-18

main-group elements

PT Group 3-12

transitional metals

PT Groups @bottom

inner-transitional metals

All non-zero #s

significant figure

All zeros to left of number

non-significant number

All zeros to right of decimal

significant figure

All zeros between numbers

significant figures

Multiplying & division

result should have the same number of significant figures as the measurement with the least number of significant figures.

Addition & Subtraction

the total number of significant figures in the answer is determined by the term with the fewest decimal places. Ex - 12.11 + 0.3 = 12.4

molar mass

the mass of one mole of a substance (g/mol). Ex - M=m/n. m=(mass)(g) n=(amount of substance)(mol)

Theory

describes why something happened

Law

describes what will happen under certain conditions

Percent composition

% element= (mass of element/total mass of compound) x 100.

Density equation

D = mass/volume.

conservation of mass equation

mass of reactants = mass of products.