MindMap Gallery Qishang Science U4_Characteristics of Matter
This is a mind map about Qishang Science U4_The characteristics of matter, including the composition of matter, Measurement of mass, density of matter, Specific heat of matter, etc.
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This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
Qishang Science U4 properties of matter
composition of matter
Matter is made up of molecules
Substances such as air are also composed of large numbers of molecules
A molecule is an extremely tiny particle that makes up matter
small volume
small quality
There are gaps between molecules
Space between molecules: gas > liquid > solid
There are gaps between the molecules that make up a substance
Molecules are in constant motion
diffusion phenomenon (Nature) molecules doing irregular movement
gas diffusion phenomenon
liquid diffusion phenomenon
The speed of liquid diffusion is closely related to temperature. The higher the temperature, the faster the liquid spreads.
Repulsion and attraction between molecules
There is not only attraction but also repulsion between molecules within a substance
Measurement of quality
quality
How much matter an object contains is expressed by mass (m)
Universal list of quality bit is kilogram (symbol is kg)
The unit larger than the kilogram is the ton (symbol t)
The unit smaller than the kilogram is the gram (symbol is g)
The unit smaller than a gram is milligram (symbol is mg)
Mass is a property of an object that does not change with changes in the object's position, shape, temperature, state, etc.
Measurement of quality
balance tray left thing right code
balance travel code Equivalent to adding a small weight to the right disk
Weighing on balance m object = m weight + m swimming code
How to use a pallet balance
1. Leveling
2.Weighing
3. After weighing, use tweezers to put the weights back into the weight box one by one.
density of matter
density
definition
For the same substance, the mass and volume increase or decrease, but the density remains unchanged.
The mass of a certain substance per unit volume is called the density of the substance
Different substances with the same volume have different masses
Density = mass/volume ρ=m/V
ρ is the Greek letter, pronounced róu. When calculating with the density formula, the units of the three quantities m, V, and ρ must be unified.
According to the definition of density, the unit of density is grams/cm³ (symbol is g/cm³) or kilogram/meter³ (symbol is kg/m³), which are read as "grams per cubic centimeter" and "kilograms per cubic centimeter" respectively. rice"
1g/cm³ =1000kg/m³
example
specific heat of matter
heat
Definition: The amount of heat absorbed or released by an object is called heat, represented by the symbol Q. The unit of heat is joule, referred to as joule, and its symbol is J. A joule is a relatively small unit of heat.
Specific heat
A large number of experiments have shown that when different substances with the same mass increase the same temperature, they absorb different amounts of heat. When the same temperature is lowered, the amount of heat released is also different. This characteristic of matter is scientifically called specific heat capacity. Referred to as specific heat. Different substances with the same mass will raise (or lower) the same temperature. Those that absorb (or release) more heat will have a greater specific heat, and those that absorb (or release) less heat will have a smaller specific heat.
The specific heat of water is greater than that of sand and gravel
Physical and chemical properties
Physical changes and chemical changes
physical changes
Matter only undergoes changes in color, state, etc., without producing new matter. This change is called physical change. For example, the mutual transformation between the three states of matter studied earlier are all physical changes.
Chemical changes
When substances change, new substances are produced. This change is called a chemical change. Chemical changes are usually accompanied by physical changes. For example, food becomes moldy, magnets attract iron powder and rust, mixing sodium hydroxide solution and sodium chloride solution, and setting off fireworks are all chemical changes.
Physical and chemical properties
physical properties
Density, color, state, odor, melting point, boiling point, hardness, ductility, thermal conductivity, electrical conductivity and other properties can be expressed by substances without chemical changes. These properties are called physical properties
chemical properties
Properties can only be expressed in chemical changes, called chemical properties
sublimation and sublimation
sublimation and sublimation
sublimation
Definition: The process of an object changing directly from a solid state to a gaseous state is called sublimation Sublimation is the process by which molecules on the surface of a solid substance overcome the attraction of other molecules to it and enter the air.
Properties: Substance absorbs heat when it sublimates
example
When dry ice powder sublimates, it absorbs a large amount of heat in the air, causing the temperature of the air to drop, causing the water vapor in the air to quickly liquefy into mist.
Why do the ends of fluorescent tubes that have been used for a long time turn black? Solid tungsten sublimates into gaseous tungsten vapor at high temperatures when the power is turned on. The gaseous tungsten vapor condenses into solid tungsten at low temperatures when the power is turned off. Since the gas will float in the lamp tube, the tungsten vapor condenses and gathers at both ends of the lamp tube. Forms black solid tungsten
Sublime
Definition: The process of matter changing from gaseous state directly to solid state is called sublimation Sublimation is the process in which gas molecules hit the surface of a solid substance and are bound by the gravity of the solid substance molecules.
Properties: Substances release heat when they sublimate
Vaporization and liquefaction
Vaporization liquid → gas
Definition: The process of a substance changing from a liquid state to a gaseous state is called vaporization
slow
evaporation
Definition: only performed on the liquid surface Works at any temperature
Influencing factors: 1.Temperature 2. Liquid surface area 3. Air flow velocity on liquid surface 4. Liquid type
Properties: liquid vaporizes, absorbs heat and cools
severe
boiling
Definition: At a certain temperature, Liquid surface and interior move simultaneously Violent vaporization phenomenon When boiling, the temperature does not Change, this temperature is the boiling point
condition: 1. The temperature reaches the boiling point 2. Continuously absorb heat
liquefaction Gaseous → liquid
Definition: The process of a substance changing from a gaseous state to a liquid state is called liquefaction
method: 1. Cool down 2. Compression volume
Properties: When gas liquefies, it releases heat and causes heat.
melting and solidification
Melting rules of sea wave and rosin
Comparing the melting of sea waves and rosin, the common point between the two is that they both absorb heat from the outside world; the difference between the two is that the melting of sea waves takes place at a certain temperature. At this temperature, the melting of sea waves takes place at a certain temperature. There will be a state where solid and liquid coexist. When rosin melts, its temperature continues to rise. It is a process of gradually becoming softer and then thinner.
Characteristics of crystalline and amorphous melting and solidification
crystal
Like sea waves, they have a certain melting temperature when melting. This type of solid is called a crystal. ·The temperature at which a crystal melts is called the melting point. Different crystals have different melting points. The melting point is a characteristic of a substance. ·The temperature of liquid crystals remains constant during the solidification process. This temperature is called the freezing point of the crystal. The melting point and freezing point of the same crystal are the same
Amorphous
·Like rosin, it does not have a certain melting temperature when melting. This type of solid is called amorphous. ·Amorphous has no melting point ·Amorphous crystals have no freezing point