# Chemistry

### Chapter 2, 3 & The TEKS

## Chapter 2, Section 2.1

Section 2.1 was mainly about mesuremets and units. Measurements and units are used daily on signs and in hospitals and gas. Miles and kilometers are two different measurements, and the united states mostly uses miles. Not all measurements are exact but scientist like them to be. A base unit is a defined unit in a system of measurement that is based on an object or event in the physical world. There are 7 base units and they are basically a defined unit in a system of measurement. there is time, length, and mass. Then we get to derived units. A derived unit is a unit that is defined by a combination of base units. There is volume, density (density= mass/volume), and temperature.

## Chapter 2, Section 2.2-2.4

Section 2.2 was about scientific notation & Dimensional Analysis. Scientific notation is an easy way to write big and small numbers. And dimensional analysis is a method of problem that focuses on the units used to describe matter. In scientific notation, you use addition, subtraction, multiplication, and division. When adding and subtracting numbers using scientific notation, the exponents have to be the same before you do the work. When you use multiplication, you multiply first factors then add exponents. When you divide, divide first factors & subtract the exponent of division from exponent of dividend. then you have your conversion factor. A conversion factor is a compansion of equal values used to express the same quantity in different units. Accuracy and precision refers to how close measured value is to accepted value.

## Section 3.1-3.4

In chapter 3 a physical property is a characteristic that can be observed or measured without changing the samples composition. Extensive properties are dependent apon the amount of substance there is, intensive properties are independent of the amount of substance present. A gas is a form of matter that flows to conform to the shape of its container & fills the entire volume of its container. The law of conservation of mass sttes that mass is neither created nor destryed during a chemical reaction- it is conserved. Filtration is a technique that used aporous barrier to separate a solid from a liquid.

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## Chapter 2 TEKS

2.1- Units Of Measurements. TEKS- (2.F)

2.2- Scientific Notation & Dimensional Analysis. TEKS- (2.G)

2.3- How Reliable Are Measurements? TEKS- (2.F)

2.4- Representing Data. TEKS- (2.H) (2.I)

## Chapter 3 TEKS

3.1- Properties of Matter. TEKS- (4.C) (4.A)

3.2- Changes in Matter. TEKS- (4.A) (8.D)

3.3- Mixtures of Matter, TEKS- (4.D)

3.4- Elements & Compounds. TEKS- (5.B) (5.A) (6.D)

## I found my resources in my TEKS packet, my book, and my notes.