Unit 2.1 - Classification of Matter

Chemistry

the study of matter, its composition, properties and the changes matter undergoes

3 states/phase of matter

solid, liquid, gas

Motions of states of matter

solid - vibrational; liquid - vibrational & rotational; gas - vibrational, rotational & translational

Pure substance

cannot be separated by physical means

Mixture

a physical combination of 2 or more substances where the substances retain their original identity ex. air, milk

Heterogenous mixture

does not have uniform compositions; individual components can be identified. ex. trail mix

Homogenous mixture

a combination of pure substances that has uniform composition and distribution of components throughout the sample

Element

the simplest form of matter and consists of identical atoms, they can’t be separated/decomposed into simpler substances by chemical or physical methods and it is either discovered or synthesized in the lab

Currently how many elements are there?

118

Elements with atomic #1-82 exist as…

stable and unstable(radioactive)

Elements greater than or equal to atomic #83 exist as…

unstable (radioactive)

What phase are most elements at room temperature?

Solid or metal

How many elements are liquid and what are they?

2; H_g (l) metal

Br₂ (l) non-metal

How many elements are gases?

11; Group 18( inert gases - unreactive) + H₂ , N₂ , 0_2, F₂ , Cl₂

Monoatomic molecules

one atom molecule; Group 18 gases

Diatomic molecules

molecule with 2 identical atoms

Metalloids

exhibit properties of both metals and nonmetals

compound

a substance formed by the chemical bonding of 2 or more different elements in a definite fixed ratio

By what methods can compounds be separated into elements?

Chemical methods not physical

Molecule

a compound or element that is covalently bonded (non-metal only)