Science chemistry

Matter

Anything that has a mass and occupies space

Pure substances

Substances that have fixed compositions and fixed properties

Element

Pure substance that are made of one type of atom

Compound

2 or more elements that are bonded together

What is the atomic number?

The atomic number is the number of protons.

What is the mass number?

The mass number is the sum of the protons and the neutrons.

What is the atomic number?

The atomic number is the number of protons.

What is the mass number?

The mass number is the number of protons + number of neutrons.

In an atom, how are protons and electrons related?

The number of protons equals the number of electrons.

What are the physical properties of metals?

1) Shiny when polished (lustrous) 2) Most are solids except mercury 3) Malleable 4) Ductile 5) High melting and boiling points 6) Good conductors of electricity and heat.

What are the physical properties of non-metals?

1) Usually dull 2) Some are solids (e.g., sulfur, carbon), some are liquids, most are gases 3) Brittle 4) Not malleable 5) Not ductile 6) Poor conductors 7) Low melting and boiling points.

What is a molecule?

A molecule is a separate unit made of 2 or more non-metal atoms bonded together. It can be an element or a compound.

What is electron configuration?

Electron configuration is the arrangement of electrons in shells around the nucleus. The first shell holds up to 2 electrons, the next two can hold up to 8 each.

What is a physical change?

A physical change is a change where a new substance is not formed.

What is a chemical change?

A chemical change is a change where a new substance is formed.

What is the evidence that electrolysis of water is a chemical change?

During electrolysis, water breaks down into hydrogen and oxygen gases. These are new substances confirmed by the pop test and glowing splint test, proving water is a compound and the change is chemical.

What is an exothermic reaction?

An exothermic reaction releases energy, such as heat, light, or sound.

What is an endothermic reaction?

An endothermic reaction absorbs energy. For example, photosynthesis requires sunlight (heat and light energy) to occur.

What are reactants in a chemical reaction?

Reactants are the substances we start with in a chemical reaction.

What are products in a chemical reaction?

Products are the new substances formed during a chemical reaction.

What does the arrow mean in a word equation?

The arrow means "changes into" or "goes to" and shows the direction of the reaction.