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how is the gas pressure pruduced in a closed container of gas?
Collisions between particles of a gas and the walls of the container casue the pressure in a closed container of gas
What three factors affect gas pressure?
temperature, volume, and the number of particles
how does increasing the temp. affect the pressure of a contained gas?
Raising the temp. of a gas will increase its pressure if the volume of the gas and the number of particles stay constant
What happens to the pressure of a gas if its volume it reduced?
Reducing the volume of a gas increases its pressure if the temp.and the number of particles are constant.
How does increasing the number of particles of a contained gas affect its pressure?
Increasing the number of particles will increase the pressure of a gas if the temperature and the volume are constant.
what are the six phase changes and describe them.
Is it endothermic or exothermic?
- melting-when the molecules are in their fixed formation energy comes and when all the molecules have enough energy to move, melting is complete.endothermic
- freezing-the average kinetic energy slows down.When all the molecules have moved slowly in an arranged pattern, freezing is complete.exothermic
- vaporation-liquid to gas endothermic
- condensation-gas or vapor to liquid exothermic
- sublimation-solid to gas or vapor without changing to liquid first. endothermic
- deposition-gas or vapor changes to solid exothermic
Describes how the kinetic energy affects the states of matter
- gas-particles in a gas move constant, random motion therfore having great kinetic energy.
- Liquid-The volume of a liquid is constant because forces of attraction keep the particles close together. Less kinetic then gas but more than solid.
- solid- vibrates only so it has less kinetic than both.
how do you determine density?
differentiate between solute, solvent and solution.
- solute- a substance whose particles are dissolved in a solution
- solvent-the soubstance in which the solute dissolves is the solvent
- solution-a mixture that forms when substances dissolve and form a homogeneous mixture.
what are the locations and charges of the three subatomic particles ?
- Protons-positively charge, found in the nucleus of an atom
- electron- negetively charged particle, found in the space outside the nucleus.
- neutron- neutral subatomic particle, and found in the nucleus of the atom
what is an element?
- Element-a substance that cannot be broken down into smaller substances.
- An element has a fixed composition because it contains only one type of atom.
how is Bohr´s model of the atom different than present day model?
Bohrs model assumed that electrons moved like planets in the solar system, but now we discovered that was incorrect. Electrons move in a less predictible way. The scientist use the eletron cloud model to describe the possible locations of electrons around the nucleus.
explain the following properties of the periodic table
Periods, groups, and families/classes.
- Periods- rows (horizontal)
- Classes- metals- good conductors of electric current and heat
- nonmetals- elements with poor cunductor
- metalloids- elements with properties that fall between those of metals and nonmetals.
Draw and lebel parts of carbon dioxide(CO2)molecule
three circles carbon in the middle
What makes an atom neutral?
If the numbers of electrons and protons are equal, the atom is electrically neutral
how can you determine the number of protons of an element using the periodic table?
elements arranged by increasing atomic number( number of protons)
Why do we use models?
Scientist model make it easier to understand things that might be too dificult to observe directly.
How do you determine the number of valence eectrons in an element?
Elements in a group have similar properties because they have the same number of valence electrons.
a system of knowledge and the methods you use to find that knowledge.
How does the process of sceince begins and ends?
IT begins with curiosity and often ends in discovery.
the use of knowledge to solve practical problems.
HOw are science and technology related?
Science and technology are independent advances in one lead to advances in the other
what are the branches of natural scicence?
Physical science, earth and space science and life science
How much matter has the universe
Very little matter
forces and motion
forces cause change in motion
Describe the difference between an observation and an inference
observation information that you obtain through your senses, and inference is when you take a conclusion of your observations
what are the properies of acids and bases
- acids- sour taste, reactivity with metals, and ability to produce color changes
- bases- bitter taste, slippery feel, and ability to produce color change in indicators.
What are the unique properties of water?
- acids donors bases acceptors
- water can act as either an asid or a base depending on the compound wich it reacts
What are the difference between solutions, suspensions, colloids, and pure substances?
- pure substances matter that always has exactly the same composition.
- solutions- homogeneous mixture(evenly distrubuted)
- suspensions- heterogeneous mixture over time it separates into layer(parts noticelby different)
- colloids- contains some particles that are intermediate in size between the small particles in a solution and the largest particle in the suspesion.
compare and contrast physical and chemical changes
- physical- some of the properties of a material change, but the substances in the material remain the same
- chemical- a substance reacts and forms one or more new sunbstances.
type of evidence for chemical change
change in color, the production of gas, and the formation of precipitate
pipette, graduate cylinder , beaker
- pipette- is a laboratory instrument
- used to transport a measured volume of liquid.
- graduated cylinder-means it has volumetric marks
- beaker-good for holding and mesuring liquids but the graduated liquids are more precise.
what do all good scientist do througout an investigation
make an observation, ask a question, develo a hypothesis, test hypothesis with experiment, analyze data and draw conclusions, hypothesis supported, develop theory