2.1 Elements, compounds and mixtures Flashcards
What is an element?
An element is a pure substance made of only one type of atom. It cannot be broken down into simpler substances by chemical methods.
How many elements are there on the periodic table?
There are 118 elements on the periodic table.
What is a compound?
A compound is a substance made from two or more elements that have chemically bonded together.
Can compounds be separated physically?
No, compounds cannot be separated physically. Chemical reactions are needed to break them into their individual elements.
What is a mixture?
A mixture is a combination of two or more substances (elements or compounds) that are not chemically bonded.
How can mixtures be separated?
Mixtures can be separated using physical methods such as filtration, distillation, or crystallization.
Give an example of an element.
Oxygen (O2) and hydrogen (H2) are examples of elements.
Give an example of a compound.
Water (H2O) and carbon dioxide (CO2) are examples of compounds.
How are compounds and mixtures different?
Compounds are chemically bonded substances, while mixtures consist of substances that are not chemically bonded.
What happens to the properties of substances in a mixture?
The properties of each substance in a mixture remain unchanged.
What is a molecule?
A molecule is a group of atoms bonded together. It can be made of the same or different types of atoms.
Can a molecule always be considered a compound?
No, not all molecules are compounds. A compound specifically has atoms of different elements bonded together, while a molecule can consist of atoms of the same element, like O2.
What is the difference between an atom and a molecule?
An atom is the smallest unit of an element, while a molecule is a group of atoms bonded together.
Give an example of a mixture.
Saltwater is an example of a mixture, as salt dissolves in water but does not chemically bond with it.
