Atomic Structure

The Structure of Matter

n Matter and energy are essential constituents of both the universe and living organisms.

n Matter is anything that has mass and takes up space.

Energy - the capacity to do work

n Matter is made of

atoms, molecules, and compounds

Atomic Structure

n Atom - fundamental unit of matter.

n 92 types of atoms found in nature, with each being composed of:

• Protons (‘+’ charge)

• Neutrons (neutral: ‘0’ charge)

• Electrons (‘-’ charge)

n Each kind of atom forms a specific type of matter known as an element.

Atoms, Molecules, & Compounds

n Atom - the smallest particle of matter still remaining the elemental properties of matter

n Molecule – a combination of two or more atoms

n Compound – a molecule made up of 2 or more kinds of atoms (elements) held together by chemical bonds

n Isotopes - atoms of the same element that differ in the number of neutrons they contain.

• Isotopes have the same number of protons & electrons, but different number of neutrons.

Water – Unique substance

n ~70% of the

weight of living

organisms

n Medium in which life's chemical reactions occur

n Liquid over a wide temperature range

n Highest surface tension

n Expands when it crystallizes, unlike most substances

n High heat of vaporization (latent heat)

n High specific heat

n Water solutions of salts, acids – electrical conductors

Дата добавления: 2015-09-01