chemistry crossword

2. A system of easy-to-use warning symbols on hazardous materials
4. Vertical column of elements in the periodic table
5. They are used to describe matter, like colour or conductivity
9. States that mass cannot be created or destroyed
10. Occurs when two or more materials react and create new materials
12. Chemical reaction that absorbs energy
13. Slow chemical change that occurs when oxygen in the air reacts with a metal
15. Number of protons in the nucleus of one atom of an element
19. Chemical reaction that releases energy
20. A table in which elements are organized by their physical and chemical properties
21. Pure substance formed when at least one metal and one non-metal combine
22. A positively charged particle
23. Chemical reaction that occurs when oxygen reacts with a substance to form a new energy and give off energy
24. Matter which has a specific composition and specific properties / every pure element

1. an atom with a neutral charge is one where the number of electrons is equal to the atomic number
3. The most reactive non-metals
5. Occurs when a material changes from one state o another
6. New substance produced in a chemical reaction between reactants
7. Elements that have both metallic and non-metallic properties
8. Pure substance formed when non-metals combine
11. Anything that has mass and takes up space
14. Horizontal row of elements in the periodic table
16. Pure substance that cannot be broken down into other substances
17. Mass of one atom of an element
18. Substance that reacts with another substance in a chemical reaction to create new substances with different propeties