CamScanner 04-15-2024 18.50 final_compressed.pdf

1 Matter is anything that has mass and takes up space. 2 The particle theory can be summarized as follows: i All matter is made up of particles. ii The particles are tiny. iii The particles are moving randomly all the time. iv There are empty spaces between the particles. v Different substances are...

1 Matter is anything that has mass and takes up space. 2 The particle theory can be summarized as follows: i All matter is made up of particles. ii The particles are tiny. iii The particles are moving randomly all the time. iv There are empty spaces between the particles. v Different substances are made up of different particles. vi Different particles have different sizes and masses. 3 The particles in matter can be atoms or molecules. 4 Atom is the basic unit of matter. 5 Most molecules are formed from two or more atoms. 1 The particle model helps describe the arrangement and movement of particles in solids, liquids and gases. Arrangement \&w-fifi*rfi% of parhcl" o.* , By State of matter e Liquid e e T - Closely packed, no regular | Small - Move around easily F , e | ~ Move freely in all | Large ~ Far apart, no pattern atall Gas | | pattern i }b e e e e e directions e ——————————— et The properties of solids, liquids and gases can be explained using the particle model. 2 b State of matter = Liquid ’ §. Shape : — ——— e Y79 ! _.,;,",3_ O TRl ‘L“,t?,_;: L ~ s - oy S NS | Particles are closely packed -> Fixed volume - Particles are in fixed positions and cannot move around -> Fixed shape E Solid | | R S R e - Each vibrates about a fixed | position Small - Closely packed in regular pattern -~ Solid B Batterns s Particles can move around -> No fixed shape Particles are closely packed | -> Fixed volume Particles can move freely -> No fixed shape Particles are far apart ' => No fixed volume — ————— —— - —— e —— — ———. —— e ——. ——— T — — e S— — a— S " i~ 1 During dissolving, the solute particles move apart and become evenly distributed among the solvent particles. solvent particle ‘ N solute particle Solute particles are surrounded and collided by solvent particles. 2 Solute particles move apart and mix with solvent particles. Solute particles are evenly distributed among solvent particles. The total mass of the solute and solvent is conserved in dissolving. Mass of solute + mass of solvent = mass of solution 3 The volume of the final solution may be different from the sum of the volumes of the solute and the solvent. 1 Most substances expand when they are heated. They contract when they are cooled. This is called thermal expansion and contraction. 2 The particles of a substance move faster during heating. This causes the spaces between the particles to increase. As a result, the substance expands. 3 The particles of a substance move slower during cooling. This causes the spaces between the particles to decrease. As a result, the substance contracts. The substance contracts. The substance expands. lower higher temperature 1 Bombardment of gas particles on a surface exerts a gas pressure on the surface. 2 When the volume of a closed container decreases, the gas becomes compressed, the gas particles bombard the container walls more often and thus the gas pressure increases. 3 Gas pressure changes with temperature. As temperature increases, gas particles move faster and bombard the container walls more often. This results in a higher gas pressure. 4 Atmospheric pressure is the gas pressure exerted by gas particles in the atmosphere. 1 The density of a substance is its mass per unit volume. 2 Objects of the same volume can have different masses. These objects have different densities. mass e volume (unit of density: g/cm’ or kg/m”) il o 4 If an object is denser than its surrounding medium, it sinks in the medium. If an object is less dense than its surrounding medium, it floats in the medium. density lower than water — floats water density higher than water — sinks @5 Density changes with temperature. Temperature ¥ Temperature 1 — liquid / gas particles move faster — density ¥ liquid / gas particles move slower — space between particles ¥ — space between particles — volume 4. | — volume ¥ — density 1