Chemistry Units 1-4 Vocab

Matter

Anything that has mass and volume (takes up space)

Atom

The smallest unit of an element, composed of protons, neutrons, and
electrons

Molecule

A group of two or more atoms held together by chemical bonds, The
atoms can be the same or different

• Compound

A substance formed when two or more different elements are
chemically bonded together in a fixed ratio

• Solid

A state of matter characterized by very strong forces holding particles
together, resulting in a definite shape and definite volume

• Liquid

A state of matter characterized by moderately strong forces holding
particles together, resulting in an indefinite shape (takes the shape of its container)
but a definite volume

• Gas

A state of matter characterized by weak, almost nonexistent forces among
particles, resulting in an indefinite shape and indefinite volume, and it is highly
compressible

• Definite

Certain; does not change unless an outside force changes it

• Indefinite

Changes based on the environment or container

• Compressible

Able to be squeezed to a smaller volume by adding pressure

• Element

A pure substance that cannot be decomposed (broken down) into simpler
substances by ordinary chemical means

• Pure Substance

Matter that contains only one type of compound or element

• Mixture

Matter that contains two or more elements or compounds that are
physically combined but not chemically bonded

• Homogeneous Mixture (Solution)

A type of mixture where the components are
evenly mixed and indistinguishable; the solute is uniformly distributed in the solvent

• Heterogeneous Mixture

A type of mixture where the components are not
uniformly distributed and can typically be seen as separate parts

• Solute

The substance that dissolves in a solution (the smaller component)

• Solvent

The larger component in a solution that dissolves the solute

• Estimated Digit

The last digit reported in a measurement, which is not certain but is an educated guess made by the observer based on the finest markings of the measuring device

• Significant Figures (Sig Figs)

The digits in a measurement that are known with certainty plus one estimated digit, indicating the precision and reliability of the measurement

• Exact Numbers

Numbers that have unlimited significant figures because they are precisely known, either by counting discrete items or by definition (e.g., some conversion factors).

• Order of Operations (PEMDAS)

An acronym (Parentheses, Exponents, Multiplication/Division, Addition/Subtraction) representing the sequence in which mathematical operations should be performed in an expression.

• Rounding

The process of reducing the number of significant figures or decimal places in a number to a specified level of precision.

• Units of Measurement

Standardized quantities used to express the magnitude of a physical quantity (e.g., meters for length, grams for mass).

• SI System (International System of Units)

The modern form of the metric system, a globally accepted standard for units of measurement used in science and commerce.

• Prefix Multipliers

Prefixes (e.g., kilo-, milli-, micro-) added to SI units to denote multiples or submultiples of the base unit, allowing numbers to be expressed on appropriate scales.

Acid

A compound that produces H + ions (hydrogen ions) when
dissolved in solution

• Anion

A negatively charged ion, typically a nonmetal

• Ball-and-stick model

A molecular model that visually represents
atoms as spheres and chemical bonds as sticks, showing the spatial
arrangement of atoms in a molecule

• Binary covalent compound

A covalent compound composed of
exactly two different nonmetal elements

• Cation

A positively charged ion, typically a metal

• Chemical formula

A concise way to represent a molecule using
chemical symbols and subscripts to show the types and numbers of
atoms present

• Chemical symbol

A one or two-letter abbreviation used to identify a specific element (eg , H for hydrogen, O for oxygen)

• Compound

A substance formed when two or more elements are
chemically bonded together

• Covalent compound

A chemical compound formed when two or more
nonmetal atoms share electrons, forming discrete molecules

• Formula unit

The simplest whole-number ratio of ions in an ionic
compound, representing the basic repeating unit in its crystal lattice

• Ionic compound

A chemical compound formed between cations
(typically metals) and anions (typically nonmetals) through electrostatic
attraction, existing in a crystal lattice structure

• Law of Constant Composition

A fundamental chemical law stating
that a pure chemical compound always contains the same elements in
the same proportion by mass, regardless of its source or method of
preparation

• Molecule

Two or more atoms held together by covalent bonds, forming
a discrete unit

• Oxyacid

An acid that contains oxygen, typically an oxygen-containing
polyatomic ion

• Polyatomic ion

A group of two or more atoms covalently bonded
together that collectively carry an overall electrical charge

• Subscript

A number written slightly below and to the right of a
chemical symbol in a formula, indicating the number of atoms of that
element in the compound

Alkali Metals

Elements in Group 1 of the periodic table; very reactive, especially
with water

• Alkaline Earth Metals

Elements in Group 2 of the periodic table; less reactive than
Group 1 but still reactive

• Anion

A negatively charged ion formed when a neutral atom gains one or more
electrons

• Atom

The smallest unit of an element that retains the chemical identity of that
element; composed of a dense nucleus containing protons and neutrons, with
electrons existing outside the nucleus

• Atomic Mass (Mass Number)

The sum of the number of protons and neutrons in an atom's nucleus. It is a whole number specific to a given isotope

• Atomic Number (Z)

The number of protons in an atom's nucleus, which
determines the element's identity

• Average Atomic Mass

The weighted average of the masses of all naturally occurring isotopes of an element, taking into account their natural abundances. This is the mass typically found on the periodic table

• Cation

A positively charged ion formed when a neutral atom loses one or more
electrons

• Dalton's Atomic Theory

A foundational theory in chemistry proposing that
elements are composed of atoms, all atoms of a given element are identical (later
refined by isotopes), atoms combine in simple whole-number ratios to form
compounds, and atoms are not created or destroyed in chemical reactions

• Electron

A negatively charged subatomic particle that exists in the space outside
the nucleus of an atom

• Elemental Symbol

A one or two-letter abbreviation used to represent an element (e.g. , O for Oxygen, Na for Sodium)

• Group

A vertical column in the periodic table, containing elements with similar
chemical properties due to similar electron configurations

• Halogens

Very reactive nonmetals found in Group 17 of the periodic table

• Ion

An atom or molecule that has gained or lost one or more electrons, resulting in
a net electrical charge

• Isotopes

Atoms of the same element (same number of protons) that have different
numbers of neutrons, and therefore different atomic masses

• Mass Spectrometer (Mass Spec)

An instrument used to measure the mass-to-
charge ratio of ions, allowing for the determination of isotopic masses and their
natural abundances

• Metalloids

Elements located along the "staircase" line on the periodic table that
exhibit properties intermediate between those of metals and nonmetals

• Metals

Elements typically found on the left and middle of the periodic table, generally characterized by being good conductors of heat and electricity, ductile, and malleable. They tend to lose electrons to form cations

• Natural Abundance

The relative proportion of a particular isotope of an element as
it naturally occurs

• Neutral Atom

An atom that has an equal number of protons and electrons,
resulting in a net charge of zero

Neutron

An uncharged (neutral) subatomic particle found in the nucleus of an atom.

• Noble Gases

Unreactive nonmetals found in Group 18 of the periodic table, characterized by their stable electron configurations

Nonmetals

Elements typically found on the upper right side of the periodic table,
generally poor conductors of heat and electricity. They tend to gain electrons to form
anions

Nucleus

The dense, positively charged center of an atom, containing protons and
neutrons

Proton

A positively charged subatomic particle found in the nucleus of an atom.