Chemistry vocabulary

4. Two or more atoms chemically bonded together; it’s the smallest unit of a compound that still has the compound’s properties.
5. A substance that reduces hydrogen ion concentration or produces hydroxide ions (OH⁻) in water; proton acceptor; pH greater than 7.
6. Atoms of the same element (same protons) that have different numbers of neutrons, and thus different masses.
8. A measure of how acidic or basic a solution is, based on the concentration of hydrogen ions; ranges from 0 (very acidic) to 14 (very basic).
9. A process where substances (reactants) are transformed into new substances (products) by breaking and forming chemical bonds.
12. A physical combination of two or more substances that are not chemically bonded and can often be separated (e.g., sand and iron filings).
13. A pure substance made of only one kind of atom, defined by its number of protons (atomic number).
16. A neutral subatomic particle in the nucleus that contributes to an atom’s mass and to nuclear stability.
17. A substance formed when atoms of different elements are chemically bonded in fixed ratios (e.g., H₂O, CO₂).
19. A substance that speeds up a chemical reaction by lowering the activation energy, without being consumed.

1. A uniform mixture where one substance (solute) is completely dissolved in another (solvent), such as salt water.
2. The combining capacity of an atom, determined by the number of electrons it can lose, gain, or share in bonding.
3. A negatively charged subatomic particle that occupies regions around the nucleus and is key to chemical bonding.
7. A positively charged subatomic particle in the nucleus; its number determines the element’s identity.
8. Arranged in recurring patterns; the periodic table organizes elements so that properties repeat at regular intervals with atomic number.
10. An atom or molecule with a net electrical charge because it has lost or gained electrons.
11. A connection between atoms in a molecule, formed when they share or transfer electrons.
14. The capacity to do work or produce change; in chemistry, often involved as heat, light, or stored in chemical bonds.
15. A substance that increases the concentration of hydrogen ions (H⁺) in water; proton donor; pH less than 7.
18. The smallest unit of an element that retains that element’s chemical properties; made of a nucleus (protons and neutrons) and electrons.