TEXTS FOR ADDITIONAL READING AND UNDERSTANDING
TEXT 1
Translate into Russian (in written form). Guess the meaning of any unfamiliar words:
A substance can be defined as a form of matter with a uniform and unchanging composition. Matter comes in three different states: solid, liquid, and gas. The physical properties can be observed without altering a substance’s composition. Chemical properties describe a substance’s ability to combine with or change into one or more new substances. Properties such as these can be influenced by external conditions like pressure and temperature.
Changes in matter can either be a physical or chemical change. A physical change alters the physical properties without changing its composition. Additionally, a chemical change or chemical reaction alters a substance’s composition. In a chemical reaction, reactants form products. During these chemical reactions, mass stays constant (i.e. mass is neither created nor destroyed). This pattern is called the law of conservation of mass.
Matter can be catergorized into two types: mixtures and pure substances. A mixture is a physical blend of two or more pure substances. Mixtures can be separated by physical means. A homogeneous mixture is called a solution. Matter also comes in the form of pure substances which can be either elements or compounds. Elements are substances that cannot be broken down into simpler substances by chemical or physical means. Elements are organized in the periodic table of elements. A compound is a chemical combination of two or more elements. A compound can be separated into its elements via a chemical change. Properties of compounds differ from the properties of their component elements. The law of definite proportions states that a compound maintains the same elemental composition in the same proportions, regardless of size, quantity, etc.
TEXT 2
Translate into Russian (in written form). Guess the meaning of any unfamiliar words:
A gas is a form of matter composed of particles in random motion. A gas will flow to conform to the shape of its container.
A liquid is also a form of matter. Like a gas, a liquid will also take the shape of its container. However, liquids have a constant volume. The forces of attraction between liquid particles limit the motion of the liquid molecules. In this way, the liquid will not expand to fill a container.
A solid is also a form of matter composed of particles in motion. However, unlike a gas and a liquid, a solid has a definite shape and a definite volume resulting from the strong forces of attraction between solid particles.
All mixtures can be separated into substances via physical changes. Substances have a definite, or fixed, composition that does not vary from one sample to another.