Semester 1 Study Guide

1. Semester 1 Study Guide

2. LAW OF CONSERVATION OF MATTER/MASS • The total mass of the materials formed is the same as the total mass of the starting materials.

3. CHEMISTRY TERMS Matter – Anything that has mass and takes up space Volume – The amount of space something takes up ( V= L x W x H) Mass – Amount of matter in an object. Weight – Measure of gravitational force exerted on an object.

4. Density – Amount of matter in a given volume (D-M/V) • Atoms – Smallest unit of an element that maintains the properties of that element. • Molecule – A neutral group of atoms held together by bonds • Element - A pure substance that cannot be broken down in to anything smaller. Can be found in the periodic table … ex. Oxygen

5. Compound – A pure substance that is made of 2 or more elements that are chemically combined. Ex. Salt • Mixture - Consists of two or more elements or compounds that are not chemically combined. Ex. Salt and pepper or oil and vinegar.

6. STATES OF MATTER • Solid – Particles are close together and only vibrate. Fixed volume and fixed shape. • Liquid – Particles are close together and can slide over one another. Fixed volume but can take the shape of the container. • Gases – Particles are far apart and have a lot of energy and movement. Changeable volume and shape.

7. PERIODIC TABLE • Table which organizes over 100 known elements • Arranged in order of increasing atomic number (tells you the number of protons in an atom) • Columns = groups – contains elements that are similar. Have similar characteristics (ex. Group 1 all reactive with water, metals, can cut easily) • Rows = periods • Mendeleev – Scientist who saw that the properties were periodic, they were in a regular pattern

8. MORE IMPORTANT PERIODIC TABLE OF ELEMENT FACTS • COMMON ELEMENTS - C – Carbon, Na – Sodium, H = Hydrogen, O = Oxygen, Fe – Iron, He – Helium and Cl – Chlorine • ZIG – ZAG LINE – Separates metal from non metals and metalloids. Metals on the left of the line. • METALS – Left of line, most are solid at room temperature, except Mercury. Malleable, good conductors, ductile and shiny

9. INTERESTING GROUP FACTS • Group 1 - Alkali metals. Very reactive metals and can cut. • Group 2 – Alkaline-earth metals. Less reactive than Alkali metals. • Groups 3 – 12 – Transition metals – Less reactive than alkali metals and alkaline – earth metals. • Group 18 – Noble gases. Do not react, have a full valance electron shell (outer shell).

10. THE ATOM • NUCLEUS – Protons (positive charge) and neutrons (neutral charge) added together = the atomic mass • SHELLS OR CLOUDS – Electrons (negative charge) • VALANCE ELECTRONS - Electrons in outer shell • The first valance electron can hold up to 2 electrons

11. PHYSICAL AND CHEMICAL PROPERTIES • Physical properties can be observed or measured – weight, mass, volume, density, color, state of matter, malleability, ductility, solubility and/or thermal conductivity. • Chemical properties – Describes a substances based on its ability to change into a new substance – flammability, how it reacts with different substances .

12. PHYSICAL CHANGES • Physical changes – change that affects one or more of the physical properties – ex. – state changes, sanding wood, breaking something, cutting your hair, oil and water, dissolving something. Substances do not change their chemical composition.

13. CHEMICAL CHANGES • Chemical changes - Change that happens when the substance changes into something new. Forms a new substance! Ex. Soured milk, oxidation (Statute of Liberty rusting), Hot gas forming when oxygen and hydrogen combine.

14. ENERGY • Energy is the ability to do work. SI units is Joules (J) • Law of conservation of energy = energy can neither be created nor destroyed. The total amount of energy in a closed system is always the same. Energy can be changed from one form to another. • Thermal energy is always produced when one type of energy is transformed into another due to friction. Example of light bulb = starts as electrical energy, it is converted to light energy, thermal energy making the bulb feel warm and thermal energy because of friction in the wire.

15. POTENTIAL ENERGY • Potential energy = the energy an object has due to its position and shape. Example a stretched bow • Gravitational potential energy = Book on a shelf. When you lift an object and go against gravity. Gravitational potential = weight multiplied by height. Expressed joules.

16. KINETIC ENERGY • Kinetic energy = energy of motion. All moving objects have kinetic energy. Depends on speed and mass. • Calculated - mass multiplied by volume squared divided by 2. More mass means more kinetic energy and more speed means more kinetic energy.

17. FORMS OF ENERGY • Mechanical energy = total energy of motion and position of an object. Potential plus kinetic. • Thermal energy = total energy of the particles that make up an object. At higher temperatures the faster the particles move. The more kinetic energy, the more thermal energy. Is affected by the amount that you have as well as temperature.

18. MORE FORMS OF ENERGY! • Chemical energy = energy of a compound that changes as atoms are rearranged to form new compounds. Is a form of potential energy. • Electrical energy = energy of moving electrons. Form of kinetic energy as the electrons move back and forth within the wires of the cord and within the parts of the devise. Example is the electrical outlets in your home.

19. THREE MORE AND WE HAVE THE FORMS OF ENERGY!!! • Sound energy – caused by an objects vibrations, work must be done to change its position. Therefore, it is a form of potential and kinetic energy. • Light energy – produced by the vibrations of electrically charged particles. Does not need particles. • Nuclear energy – energy associated with changes in the nucleus of an atom. Two ways: when 2 nuclei join together example is the sun or when a nucleus splits apart. Example - getting energy from Uranium to generate electricity at a nuclear power plant.

20. HEAT • Heat is the transfer of energy between objects of different temperatures. • Conduction – transfer from one substance to another through DIRECT contact. Example is a spoon heating up in a bowl of soup. The particles collide and those with more kinetic energy transfers to the lower kinetic energy particles. Needs particles. • Convection – transfer of thermal energy by the movement of a liquid or gas. Example is the boiling of water in a pan. The warmer water rises as it is less dense and the cooler, more dense water falls to replace it. Needs particles

21. A LITTLE MORE ABOUT HEAT • Radiation – Does not need particles. The transfer of energy through matter or space as electromagnetic waves. Example the sun emits visible light so that we can see.

22. WAVES • Wave is any disturbance through matter or space. • ONLY energy is carried by waves.

23. MECHANICAL WAVES • Needs a medium through which to travel • Longitudinal and surface waves • When the particle vibrates it makes the particle next to it vibrate, this is how the energy is carried along

24. LONGITUDINAL WAVES • The particles of the medium vibrate back and forth. • Compression = when the particles of the wave are crowded together • Rarefaction = when the particles of a wave are spread apart. • Example is a sound wave

25. SURFACE WAVES • Surface wave is when a transverse and a longitudinal wave combine. The particles move in circles. • Example is ocean waves.

26. ELECTROMAGNETIC WAVES (EM WAVES) • Do NOT need a medium. They can travel through solid, liquid and gases but are fastest through a vacuum.

27. TRANSVERSE WAVES • The particles vibrate with an up and down motion. Particles move perpendicular to the wave. • Highest point on the wave is the crest and lowest point is the trough. • Wavelength = the distance from one crest or trough to the adjacent crest or trough • Amplitude = the distance from the rest position to the crest or trough. Height of the wave. Higher the amplitude more the energy.

28. MORE ON TRANSVERSE WAVES • Frequency = the number of waves produced in a given amount of time. Measured in Hertz. The higher the frequency the shorter the wavelength and the higher the energy. • Wave speed = speed at which the wave travels

29. LIGHT • Is an electromagnetic wave • Produced by the vibration of electrically charged particles. The vibration of an electric and magnetic field together produce the wave. • Speed is 300,000,000 m/s through a vacuum (space) faster than sound • The electromagnetic spectrum contains the entire range of EM waves. Separated by wavelength and therefore frequency. Radio waves have the longest wavelength and therefore least energy. Gamma have the smallest wavelength and therefore most energy. Visible light is the only wavelength that we can see.

30. REFLECTION • Light or any other wave bounces off an object. • Law of Reflection – The angle of incidence is equal to the angle of reflection • Regular reflection – example is a mirror. Can see your reflection as the beams of light reflect off at the same angle. Smooth surfaces. • Diffuse reflection – light is scattered in many directions. Rough surfaces

31. REFRACTION • The bending of a wave as it passes at an angle from one medium to another. This is due to the speed of the wave. Examples include a prism separating white light into the colors of visible light and a straw, pen or pencil in water.

32. ABSORPTION • Absorption is the transfer of energy carried by light waves to particles of matter. Example – the flash light becomes dim as the particles absorb light.

33. COLOR • Opaque – objects do not transmit any light through them. They reflect the color you see and absorb the remaining colors. • Transparent – objects let light easily through them. Example – you see a green bottle- green is transmitted through the bottle and all others are absorbed. • Translucent – objects transmit light but scatter it. Example – wax paper.

34. SOUND • Travels as a longitudinal wave. Needs a medium • Travels fastest through solids, as particles are closer together. • The speed of sound depends on temperature, the higher the temperature the faster the speed. • The higher the frequency of the wave the higher the pitch. Humans can only hear frequencies between 20 and 20,000 hertz – above or below this range (on average) humans can not hear.

35. A LITTLE MORE SOUND • Increase amplitude and you increase the loudness of the sound. Measured in decibel. • Reflection of a sound wave creates echoes. Echolocation used to locate objects under water. • Resonance occurs when an object vibrating at or near the resonant frequency of a second object causes the second object to vibrate. • Noise = any undesired sound, especially a nonmusical sound, that include a random mix of pitches.