elements, compounds and mixtures - chapter 4

what are elements?

they are substances that cannot be broken down into simpler substances

what are atoms?

they are the smallest unit of an element

what is the smallest atom?

hydrogen

what is the largest atom?

potassium

what are molecules?

they are a group of two or more atoms chemically combined together

what are compounds?

they are a substance containing two or more elements chemically combined together

what energy is given out when elements combine together to form a compound?

heat energy

what are the two kinds of particles found in a compound?

molecules and ions

what are ions?

an atom or a group of atoms that have an electrical charge

what are compounds made up of ions called?

ionic compund

what are mixures?

they are a combination of two or more substances that are not chamically combined together

composition of compound

has a fixed position by mass

composition of mixture

has a variable composition by mass

melting and boiling point of compound

has fixed melting and boiling points

melting and boiling point of mixture

has variable melting and boiling points

properties of compound

has its own physical and chemical properties which are different from its elements

properties of mixture

does not usually have its own properties; it has the same properties as its components

separation of compound

cannot be separated into two or more other substances by physical means; a chemical reaction is needed to separate the elements

separation of mixture

can be easily separated into its components by physical means without a chemical reation