Material properties don't change - density, magnetism, color, hardness, texture
What is density?
a measure of the amount of matter in a given volume - a physical property of a material
What is the calculation for density?
mass divided by volume
Does the density of a material change based on it's size?
What is buoyancy?
the ability of an object to float - if an object floats, it is buoyant
What determines an objects buoyancy?
the density of both the object and the liquid
If the object's density is __________ than the liquid's density, it will float.
If the object's density is __________ than the liquid's density, it will sink.
Is ocean water more or less dense than fresh water? Why?
because it has salt in it
What is an atom?
the smallest particle of an element that still has the properties of the element
Are atoms different for different elements?
Are atoms too small to be seen (even with a microscope)?
The properties of atoms determine the properties of an element - TRUE OR FALSE
What is the center of an atom called?
What are found in the nucleus of an atom?
neutrons and protons
What is a neutron?
has no electrical charge
What is proton?
has a positive charge
An atom is identified by the number of _____________ it has.
What are electrons?
they move around the protons and neutrons and have a negative charge - they can join or leave atoms, or be shared between atoms
Elements are organized in a table called the ____________________.
Periodic Table of Elements
Describe the rows and columns of the periodic table of elements.
elements are arranged in the rows according to # of protons
elements are arranged in columns according to chemical properties
What are molecules?
When atoms combine with other atoms
Do atoms sometimes share electrons in some molecules?
Many substances are found in nature as molecules, not as single atoms. TRUE OR FALSE
What is a compound?
a type of matter made of a combination of elements
Are properties of compounds different from the properties of elements that make them up?
Example - water is a liquid at room temperature, but the elements (hydrogen and oxygen) that make up water are invisible gases
What is a chemical formula?
shows how many atoms of each element are in a compound
Water is H2O - has 2 hydrogen atoms and 1 oxygen atom
What is the formula for carbon dioxide?
What does carbon dioxide form at really cold temperatures?
dry ice - carbon dioxide can also be used to put out fires
What forms salts?
compounds in which particles are held together by opposite charges
What do all salts have in common?
have at least one kind of metal element and one kind of non-metal element
they can form cystals
Describe the elements that make up table salt
sodium (can cause an explosion alone in water) and chlorine (is a poisonous gas) - together though they form a brittle white solid (salt) that we can eat
MATTER is composed of ATOMS, which are bonded together to make MOLECULES. ELEMENTS are composed of only one kind of ATOM. ATOMS of different elements are bonded together to form COMPOUNDS. If ATOMS are aligned in perfect 3-dimensional arrangement, they form CRYSTALS.
What determines whether a material is a solid, liquid, or gas?
the arrangement and motion of its atoms or molecules
What are the 3 phases or states of matter?
Liquid, gas, or solid
Describe a solid
definite shape and volume
particles vibrate in place and are very close together
As a solid warms up it becomes a liquid - describe liquid
forces hold the particles together but they can move about
they do not have their own shape
What is the freezing point or melting point?
the temperature at which a liquid freezes or melts
Is the freezing point different for different materials? Give an example
Yes - salt water has a lower freezing point than fresh water
Materials change size when their temperatures change. TRUE OR FALSE
The hotter the material the more the particles move about and have more space between them so that is why the material gets bigger. TRUE OR FALSE
What are the properties of gases?
does not have a definite shape or volume
particles are far apart
gases can be squeezed
When does evaporation occur?
when particles go from liquid to gas - higher temperature
When does condensation occur?
when a gas turns into a liquid
Even when something is frozen, do the particles stop moving/vibrating?
NO - they still vibrate
So when something goes from a gas to liquid to solid - what changes in the spacing of the particles?
The particle spacing is wider in a gas and gets smaller in a liquid and even smaller in a solid
What is a mixture? Give an example.
different materials placed together but do not bond to form compounds - they can usually be separated again
Example - salt and pepper mixed together - they can be separated again by placing the salt and pepper mixture in water - the pepper will float then you can heat the salt water to get the salt
Many metals are mixtures called _____________.
What is a solution? Give an example
A special mixture where substances are spread out equally and will not settle
In a solution, the substance that dissolves is called the _______________
The ____________ is the substance in which the solute is being dissolved.
Solvent (water = universal solvent)
What two things will help a solute dissolve faster in a solvent?
stirring or heating
Not all solutions are made by dissolving a solid in a liquid. TRUE OR FALSE
What are 3 ways to describe a solution?
saturated - has the most solute allowed without changing the temperature
concentrated - has a medium amount of solute - close to being saturated
dilute - has least amount of solute
Will salt dissolve in oil?
What causes a solid to melt to a liquid and then a gas