Unit 2 Flashcards
(28 cards)
What is matter?
Anything that has mass and occupies space.
What is the smallest unit of matter?
Atom.
What are the five main ideas of the Particle Theory of Matter?
- All matter is made up of particles.
- Particles are in constant motion.
- The energy of particles increases with temperature.
- There are spaces between particles.
- Particles attract each other.
How do particles behave in solids?
Particles are closely packed and vibrate in fixed positions.
How do particles behave in liquids?
Particles are close together but can move past one another.
How do particles behave in gases?
Particles are far apart and move freely.
What happens to the energy levels of particles when changing states?
Energy levels increase when a substance changes from solid to liquid to gas.
How do changes in energy cause a substance to change its state?
Increase in energy can cause a solid to melt into a liquid, while a decrease can cause a gas to condense into a liquid.
What is the difference between physical and chemical properties of matter?
Physical properties can be observed without changing the substance, while chemical properties involve a change in the substance.
Can you give examples of qualitative physical properties?
- Color
- Odor
- Texture
Can you give examples of quantitative physical properties?
- Mass
- Volume
- Density
What are signs that a chemical change has occurred?
- Change in color
- Production of gas
- Formation of a precipitate
- Change in temperature
Who created the periodic table?
Dmitri Mendeleev.
How are elements arranged on the periodic table?
By increasing atomic number and similar properties.
What are the key characteristics of Group 1 elements?
- Highly reactive
- Alkali metals
- One electron in the outer shell
What are the key characteristics of Group 2 elements?
- Reactive
- Alkaline earth metals
- Two electrons in the outer shell
What are the key characteristics of Group 17 elements?
- Very reactive
- Halogens
- Seven electrons in the outer shell
What are the key characteristics of Group 18 elements?
- Inert gases
- Full outer shell
- Generally non-reactive
How does the periodic table reflect trends in reactivity?
Reactivity increases down a group and decreases across a period.
What were the major contributions of Democritus to atomic theory?
Proposed that matter is made of indivisible atoms.
What were the major contributions of Dalton to atomic theory?
Developed the atomic theory and postulated that atoms combine in fixed ratios.
What were the major contributions of Thomson to atomic theory?
Discovered the electron and proposed the ‘plum pudding’ model.
What were the major contributions of Rutherford to atomic theory?
Discovered the nucleus through gold foil experiment.
What were the major contributions of Bohr to atomic theory?
Proposed that electrons orbit the nucleus in fixed paths.
