Chemistry (H) Final Exam 24-25

Physical Change

A change in size, shape, or state to the physical properties of a substance where no new substance is made.

Physical Property

A characteristic of a substance that can be observed with sense and determined without destroying matter.

Chemical Change

A change in a substance’s physical and chemical properties, creating a new substance.

Chemical Property

A characteristic of a substance which indicates how a substance reacts with something else. Matter will be changed into a new substance after the reaction.

Malleability

The ability to be hammered into a thin sheet.

Chemical Formula

A representation of different chemical compounds.

Element

A collection of particles consisting of atoms that are all the same.

Atom

A particle of matter.

Pure Substance

Matter that has only one set of chemical and physical properties.

Product

The substance formed as a result of a chemical reaction.

Period

-Horizontal row of chemical elements

-Do not have similar properties

-First Element in a Period: Extremely active

-Last Element in a Period: Inactive gas

Metal

-Left and middle sections (trans.) of the period table

-Elements which loose electrons easily

-High thermal and electrical conductivity

-Ductile, Malleable, Lustrous, High tensile strength

Atomic Number

-How many protons an atom, of an element, has.

-Located near the top left corner of an element

-Unique to each element, no two elements have the same atomic number

Matter

Anything that has mass and takes up space.

Boiling Point

The temperature at which a substance changes from a liquid state to a gas at a given pressure.

Homogeneous

Components evenly mixed together and part cannot be seen separate (pure).

Heterogeneous

Components unevenly distributed (impure).

Mixture

Two or more pure substances mixed together. Each substance in the mixture retains its own set of chemical and physical properties.

Compound

Two or more elements chemically bonded together.

Particulate Level

Observing matter at the level of their atoms and molecules.

Macroscopic

Observing matter that is large enough to be observed by the unaided eye.

Reactant

The original substance which undergoes a chemical or physical change during a reaction.

Atomic Mass

-The mass of both protons and neutrons combined in a nucleus.

-Located on the top right of an element.

Ionic Bond

-An atom attracts electrons a lot more than another

-The electron is considered to be transferred from one atom to the other.

-Between a metal and non-metal

-Big differences in electronegativity

Halogens

-Most reactive non-metal (7 valence electrons)

-Never found free in nature

-Reacts with Alkali metals to form salt

-Located in group 17

Noble Gases

-Colorless gases that are extremely un-reactive

-Inactive due to the outermost shell being full (8 Valence Electrons)

-Inert: don’t form with other elements to form compounds

Molecule

A particle with two or more atoms joined by a chemical bond.

Subscript

A number printed below the line type which indicates the total atoms of a given element in a chemical compound.

Coefficient

The number placed in front of a chemical formula to indicate the number of molecules of a substance involved in the reaction.

Percent Composition

-Percent by mass of each component in a material.

-Part mass/Total mass x 100

Stoichiometry

The study of quantitative relationships between the amounts of reactants use and amounts of products formed by a chemical reaction.

Molar Mass

The mass of one mole of a substance.

Proton

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

Neutron

An uncharged subatomic particle found in the nucleus of an atom (except for hydrogen).

Synthesis Reaction

-A compound made from simpler material.

-A + B → AB

Decomposition Reaction

-A compound broken down into simpler compounds, or all the way down to the elements that make it up.

-AB → A +B

Single Replacement Reaction

-One element that starts out by itself replaces another element in a compound, kicking it out. 

-A + BC → B + AC

Double Replacement Reaction

-The positive and negative ions in two compounds switch places.

-AB + CD → AD + BC

Combustion Reaction

-A compound containing carbon and hydrogen (and sometimes oxygen) combines with oxygen gas to produce carbon dioxide and water. 

-Burning

-CxHy(O2) + O2→ CO2 +H2O

Non-metals

-Elements lacking the characteristics of metals.

-Poor conductors of heat and electricity.

-Not ductile or malleable.

-Many are gasses, solids are brittle and break easy.

Combustibility

-Burning.

-The property of a substance that can burn or react with an oxidant to produce light and heat.

Polar Covalent Bond

-Separated Positive and negative charges in the same bond

-Electrons shared unequally between atoms

-Occurs between non-metals with different electronegativities

-0.4 < EN < 2.0

Non-Polar Covalent Bond

-Two electrons are shared equally

-Strong bonds within a Molecule, weak attractions between molecules

-Low melting/boiling points

-Generally wont dissolve in water

-Poor electrical conductors

Metallic Bond

-Electrons shared among atoms

-Occurs between metals

-Metal cations in a ‘sea’ of electrons

-Malleable, ductile, lustrous, electrical conductors

Ductility

The ability to be pulled into wires.

Independent Variable

The variable being tested (x-axis).

Dependant Variable

The data measured in response to the changed caused by the independent variable (y-axis).

Electrons

Negatively charged subatomic particle.

Constant

A value that doesn’t change or vary.

Control

A standard variable not exposed to the experimental treatment. Used as a comparison point.

Valence Electron

The electrons of an atom located in the outermost shell.

Groups

The vertical Columns (location) of elements that share similar chemical properties (Same number of VA).

Balancing Equations (solving)

1) Write equation

2) Add coefficients (a,b,c,d..)

3) Break it down (algebraically)

4) Atom inventory

Predicting Products (solving)

-Single Replacement: A+BC→B+AC

-Double Displacement: AB+CD→AD+CB

-Combustion Reaction: CxHy (o2) → CO2+H2O

Stoichiometry (Solving)

-Grams to grams: Molar mass

-Moles to moles: Mole ratio

-Moles to grams: Mole ration > molar mass

-Grams to liters: Molar volume > molar mass > mole ration

Molar Mass

1) Rewrite the numbers of atoms of each element separately

2) Multiple the number of atoms of one element by the atomic mass of that element

3) Add the sums together

Unit: g/mol

Naming Ionic Compounds (Solving)

1) Identify cation and anion

2) Name the cation first, by its elemental name

3) Name the anion by using the first syllable of its elemental name followed by ‘ide’

4) Write the name of the cation first and the name of the anion second

Electronegativity and Determining Bond type (Solving)

-Find the electronegativity for each atom and subtract the two values (biggest ones always first, or absolute value).

-Ionic: >2

-Polar Covalent: between 0.5 to 1.9:

-Non-Polar Covalent: 0.4 or less

Reactivity of Metals (Solving)

-Metal reactivity (activity) series: List of metals from most to least reactive.

-Metal: M & Ion: I

-M/I: If the metal is above the Ion, it WILL react

-I/M: If the Ion is above the metal, it WILL NOT react

Types of Chemical Reactions (Solving)

-Synthesis: A+B→ AB

-Decomposition: AB→ A+B

-Single Replacement: A+ BC →AC + B

-Double Replacement: AB+CD→ AD+ CB

-Combustion: Substance + O2 → CO2 + H2O

Particulate Level Models (solving)

1) Each element is represent by a different type of circle

2) Determine a key

3) Include ‘+’ and ‘→’ symbols

Naming Covalent Compounds (solving)

-Use numerical prefixes to indicate the number of atoms of each element.

-Change the ending of the second element to ‘ide’