The particle theory of matter

• Matter is anything that has mass and takes up space
• All matter can be classified as either a pure substance or a mixture
• The study of matter and its changes is called chemistry
• Particle Theory of Matter:

  • Everything is made of particles
  • There are spaces between the particles
  • Particles are attracted to each other
  • Temperature affects the speed at which particles move
  • Particles are always moving because they have kinetic energy
  • There are different kinds of particles, but all particles of one substance are identical
• Solids:

  • Particles in solid form are close together
  • Particles are strongly attracted to each other and vibrate in place
  • Solids have a fixed shape and volume
  • Spaces between particles are small
• Liquids:

  • Particles in liquid form are slightly farther apart
  • Particles are less attracted to each other and can slide past each other
  • Spaces between particles are larger than in a solid
• Gases:

  • Particles in gas form are far apart and can move in any direction
  • Attraction forces between gas particles are weak
  • Gases have no fixed shape or volume and expand to fill their container
• Particle Theory:

  • All matter is made up of tiny particles that are constantly moving
  • The speed at which particles move depends on the state of matter
• Atoms:

  • Atoms are the smallest particles and the building blocks of matter
  • Elements are single atoms or two or more of the same type of atoms bonded together
• Molecules:

  • A molecule is a group of atoms bonded together
  • Compounds have more than two atoms bonded together and are made of different elements combined
• Pure Substances:

  • Made of just one element or one compound
  • Examples include hydrogen, water, sugar, table salt, baking soda, aluminum, and gold
• Protons:

  • Found in the nucleus of an atom with a positive charge
  • The number of protons determines the element
• Neutrons:

  • Found in the nucleus with no electrical charge
  • The number of neutrons can vary, but the number of protons is constant for a given element
• Electrons:

  • Orbit the nucleus with a negative charge
  • Determine the chemical properties of atoms and how they react with other atoms
• Nucleus:

  • Central region of the atom containing protons and neutrons
  • Surrounded by a cloud of electrons orbiting the nucleus
• Periodic Table of Elements:

  • Shows all known elements in the universe
  • Organizes elements by chemical properties
  • Elements are organized by atomic number
• Periods (Rows):

  • Elements in a row have the same number of electron shells
  • Each period corresponds to the number of electron shells for the elements in that row
• Groups (Columns):

  • Elements in a group have the same number of valence electrons
  • Elements in the same group share similar characteristics
• Categorizing Elements:

  • Elements can be categorized based on different properties
  • Common ways include using the periodic table and classifying as metals, nonmetals, or metalloids
• Metals:

  • Good conductors of heat and electricity
  • Generally solid at room temperature
• Nonmetals:

  • Poor conductors of heat and electricity
  • Can be gases, liquids, or solids at room temperature
• Metalloids:

  • Properties intermediate between metals and nonmetals
  • Located between metals and nonmetals on the periodic table
• Reactive & Non-Reactive Elements:

  • Elements can be classified based on their reactivity
• Reactive elements tend to participate in chemical reactions by losing or gaining electrons to form new compounds
• Unreactive elements do not readily participate in chemical reactions and tend to remain unchanged
• Reactive elements combine with other elements to form compounds
• Examples of reactive elements include chlorine, hydrogen, sodium, potassium, nitrogen, and lithium
• Pure substances are composed of a single type of atom, molecule, or ion
• There are two main types of pure substances: elements and compounds
• An element is made up of a single type of atom, such as hydrogen, oxygen, or gold
• A compound is made up of two or more elements that are chemically combined, such as water (H2O), salt (NaCl), or methane (CH4)
• Mixtures are made up of two or more pure substances that are physically combined, but not chemically combined
• Pure substances have a fixed composition, while mixtures can have varying compositions depending on the proportions of the pure substances that are combined
• Particles in matter have spaces between them, with particles attracting each other and having more energy at higher temperatures
• Mixtures can be either homogeneous or heterogeneous
• Particles in matter are always in motion, with higher temperatures leading to more kinetic energy and faster movement
• Particles in all matter are composed of tiny particles that are too small to be seen with the naked eye
• Changes of state in matter involve the breaking or forming of bonds between particles
• Examples of mixtures include air (a mixture of gases), concrete (a mixture of cement, sand, water, and aggregate), and stainless steel (an alloy made of iron, chromium, and other elements)
• Homogeneous mixtures look like only one type of particle, while heterogeneous mixtures are made up of two or more types of particles that are not uniform