To sort things into groups by what they have in common.

To share ideas, results, or information with others.

To look at how two or more things are alike and different.

To decide something based on evidence.

Observations or measurements collected to investigate a question.

A process engineers use: plan a solution, build and test it, then use what you learn to improve it.

A person who uses science and math to design and build solutions to problems.

Observations or measurements used to support or question a claim or explanation.

To decide something from clues and evidence.

To figure out what information means.

To study something carefully to find out about it.

To explain the reasons behind a claim, using evidence to back it up.

To find the size or amount of something using a tool.

To use your senses or tools to notice details.

To arrange things in a clear order.

A prediction states an expected outcome. A hypothesis is a proposed explanation that can be tested with evidence.

A request for information that can guide an investigation.

To write down what you see or measure.

To find and explain a connection between two or more ideas.

A way of studying the natural world using observation, evidence, and testing.

Describes a water-based solution with more hydrogen-ion activity than a neutral solution; its pH is below 7 at 25 °C.

A solution’s ability to react as an acid; pH describes hydrogen-ion activity and does not by itself measure total acid content.

The capacity of water to neutralize added acid; it is different from pH.

The smallest unit of an element that keeps that element’s chemical identity.

Describes a water-based solution with a pH above the neutral value, which is 7 at 25 °C.

How matter can change form: a physical change alters shape or state without making a new substance, while a chemical change creates a new substance entirely.

A short way to write a chemical reaction using symbols, showing what you start with and what forms.

A substance made of two or more elements joined together chemically, like water (H₂O).

The rule that matter is not created or destroyed in a change, so the total mass stays the same.

A pure substance made of one kind of atom; chemical reactions cannot break it into simpler substances.

A column on the periodic table. Elements in the same column have similar properties.

A column on the periodic table. Elements in the same column have similar properties.

A substance or observation that signals a condition or change; an acid–base indicator changes color over a particular pH range.

An acid–base indicator paper that turns red in acidic conditions and blue in basic conditions; it does not give an exact pH.

An element that is usually shiny, can be bent, and conducts heat and electricity well.

Two or more substances mixed together but not joined chemically, like trail mix or salt water.

A group of two or more atoms held together by chemical bonds.

Describes a water-based solution with equal hydrogen- and hydroxide-ion activities; its pH is 7 at 25 °C.

Group 18 elements, which usually have very low chemical reactivity under ordinary conditions; some can form compounds.

An element without the typical combination of metallic properties; many conduct electricity poorly, but exceptions exist.

A chart of the elements arranged by increasing atomic number, with recurring patterns in properties.

A row across the table of elements, read from left to right.

A number describing how acidic or basic a water-based solution is; lower values indicate greater acidity.

A way to express acidity and basicity numerically. Many dilute water-based solutions fall between 0 and 14, but values can extend beyond that range.

Matter changing between solid, liquid, and gas. The particles change how they move and how far apart they are.

An acid–base indicator that is colorless in acidic and near-neutral solutions and pink over a range of basic conditions.

A trait that describes a material and helps you tell it apart from others.