ATI TEAS Chemistry Comprehensive Review

What is an atom?

An atom is the smallest unit of an element that retains that element's properties. It consists of protons, neutrons, and electrons.

Which subatomic particle has a positive charge?

The proton has a positive charge (+1).

Memory Tip: P = Proton = Positive

Which subatomic particle has no charge?

The neutron has no electrical charge (neutral).

Memory Tip: N = Neutron = Neutral

Which subatomic particle has a negative charge?

The electron has a negative charge (-1).

What determines the identity of an element?

The number of protons (atomic number) determines the element.

What is the atomic number?

The atomic number equals the number of protons in an atom. It uniquely identifies the element and its position on the periodic table.

ATI Memory Tip: PAN

• Protons

• Atomic

• Number

How do you calculate the number of neutrons?

Neutrons = Mass Number − Atomic Number

What is an element?

An element is a pure substance made of only one type of atom. Elements cannot be broken down into simpler substances and are represented on the periodic table.

What is a molecule?

A molecule is formed when two or more atoms are chemically bonded together. Molecules can consist of the same or different elements and are the smallest unit of a chemical compound.

What is a compound?

A compound is a substance formed when atoms of different elements chemically bond together.

Ex. H₂O, CO₂, NaCl

What is the difference between a molecule and a compound?

A molecule is any two or more atoms bonded together, while a compound specifically refers to a molecule made up of different elements.

What is an ion?

An ion is an atom or group of atoms with a charge due to gaining or losing electrons.

What is a cation?

A positively charged ion formed by losing electrons.

Example: Na⁺

Memory Tip: Cat-ions are Paws-itive

What is an anion?

Answer: A negatively charged ion formed by gaining electrons.

Example: Cl⁻

What is a physical change?

A change in appearance or state without changing chemical composition.

Examples:

• Melting ice

• Boiling water

• Breaking glass

What are signs of a physical change?

Signs of a physical change include changes in shape or size, phase transitions (like melting or boiling), and alterations in texture or color, without any change to the chemical identity of the substance.

What is a chemical change?

A process where substances undergo a transformation resulting in the formation of new chemical substances, often indicated by color change, gas production, or temperature changes.

What are signs of a chemical change?

Signs of a chemical change include color change, gas production (bubbles or odor), formation of a precipitate, and energy changes, indicating a new substance is formed.

Is burning wood a physical or chemical change?

Chemical change because new substances (ash, gases, smoke) are produced.

Is melting ice a physical or chemical change?

Physical change because water remains H₂O.

What is an acid?

An acid is a substance that donates protons (H⁺ ions) in a solution and typically has a sour taste. Acids have a pH less than 7 and can react with bases to form salts and water.

What is a base?

A base is a substance that accepts protons (H⁺ ions) in a solution, typically has a bitter taste, and a pH greater than 7. Bases can react with acids to form salts and water.

What is an alkali?

An alkali is a subset of bases that are soluble in water and release hydroxide ions (OH⁻) in solution. Common examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH).

What is the pH scale?

The pH scale is a logarithmic scale used to measure the acidity or alkalinity of a solution, ranging from 0 to 14. A pH of 7 is neutral, values below 7 indicate acidity, and values above 7 indicate alkalinity.

What pH is considered neutral?

A pH of 7 is considered neutral on the pH scale, indicating a balance between acidity and alkalinity.

Which pH values are acidic?

Acidic pH values are those below 7 on the pH scale, indicating a higher concentration of hydrogen ions (H⁺) in the solution.

Which pH values are basic (alkaline)?

Basic (alkaline) pH values are those above 7 on the pH scale, indicating a lower concentration of hydrogen ions (H⁺) and a higher concentration of hydroxide ions (OH⁻) in the solution.

What happens during a neutralization reaction?

In a neutralization reaction, an acid and a base react to form water and a salt, typically resulting in a solution with a pH closer to neutral.

What happens to pH as a solution becomes more acidic?

pH decreases.

What is the difference between an element and a compound?

An element contains one type of atom; a compound contains two or more different elements chemically bonded together.

What happens to pH as a solution becomes more basic?

pH increases.

What is the pH of blood?

Approximately 7.4 (slightly basic).