3.1 Chemistry developed out of interest in materials The ability to control fire allowed ancient people to prepare copper(7000 years ago) and iron (3200 years ago) for tools and weapons

Acid-base reaction: Transfer of proton Oxidation and reduction: transfer of electron

10.1 Acids donate protons, bases accept them Sulfuric acid is the number one manufactured chemical 85 billion pounds (40,000,000tons) annually in US. Acid has “sour taste

Chapter 1 Chemistry is a Science of Change water molecule is consisted of one oxygen(氧) atom and two hydrogen(氢) atoms A cup of water contains about 1024 water molecules

The atmosphere layer is very thin compared to the size of the Earth

Golden rice: two European scientists created a new strain of rice enriched in B-carotene, which the body uses to make vitamin A. This is a kind of transgenic plant(转基因植物)

I. Choose the Correct Answer 1. Which statement is most correct? (C) (A)Uniform circular motion causes a constant force toward the center. (B)Uniform circular motion is caused by a constant force toward the center

I. Choose the Correct Answer 1. An object is moving along the x axis with position as a function of time given by x=x(). Point is at x 0. The object is definitely moving toward O when

A reference frame consists(1)a coordinate system and(2)a set of synchronized clocks distributed throughout the coordinate grid and rest with respect to it

一.简谐振动 1.运动方程和振动曲线