Sections 1.3 and 1.4 Science 7 Mr. Nigh Matter and Energy Sections 1.3 and 1.4 Science 7 Mr. Nigh

Matter Combines to form different substances Most of the substances in the world are mixed Matter can be pure or it can be two or more substances mixed together Drinking water may appear to be pure, but may have many minerals dissolved in it. Often the difference between pure and mixed may only be visible on the atomic or molecular level

Elements An element is a substance that contains only a single type of atom The number of atoms is not important An element cannot be separated into other substances

Gold Silver

Compounds Compounds are substances that consist of two or more different types of atoms bonded together Some types are made of molecules such as water and carbon dioxide Others are made of elements bonded together like salt

Salt

Salt is a compound that has very different properties then the elements that make it up Sodium and Chlorine are poisonous by themselves But when combined, they create a compound (table salt) that is safe to eat

Mixtures A mixture is a combination of different substances that remain the same individual substances and can be separated by physical means For example: a fruit salad is not a different kind of fruit, the parts can be separated by physical means

Fresh Fruit Salad

Parts of mixtures can be the same or different throughout Soil Several handfuls of soil may have different properties in different parts of your backyard The soil in the yard is thus an example of a heterogeneous mixture, different properties in different parts of the mixture

Soil Layers

Kool-aid You know the color and flavoring in Kool-aid are there because you can see and taste them One drop of the liquid is essentially the same as another drop Thus this is an example of a homogeneous mixture

Comparing mixtures and compounds Substances in mixtures remain the same, in compounds new substances are formed by atoms that bond together Mixtures can be separated by physical means, compounds only by breaking bonds Proportions in mixtures vary, compounds are fixed because the type and number of atoms are always the same

States of Matter The four familiar states of matter are solid, liquid, gas and plasma When a substance changes from one state to another, the molecules in the substance do not change However the arrangement of molecules does change giving each state of matter its own characteristics

Solid It has a fixed volume and a fixed shape Particles are close together and form a regular pattern Particles cannot move from one location to another, fixed

Liquid Liquid has a fixed volume, but no fixed shape Usually the shape of the container it is in Particles are attracted and close, but are not fixed and may move from one place to another

Gas A gas has no fixed volume or shape Particles are not close together and may move from one place to another Space between particles can increase or decrease with pressure

Gas Behavior Gas molecules are always in motion, continually hitting each other and applying pressure to the sides of any container they are in As in a bicycle tire, the more molecules are put in, the harder the outside of the tire becomes The speed at which gas molecules move depends on the temperature, higher temperature molecules move faster

Plasma Although it is the least familiar state of matter to us here on Earth, plasma is actually the most common form of matter – 99% of all visible matter in the Universe. In a plasma, a significant number of electrons have such high energy levels that no nucleus can hold them.

Earth Plasma examples

Plasma in the universe Horsehead nebula Orion Nebula

Egg Nebula

Plasma on the Sun

--Difficult Concept-- Listen Volume, temperature, and the pressure of gasses have a unique relationship --Difficult Concept-- Listen Increase Decrease Stay the same

If the temperature of the gas stays the same, increasing the pressure of the gas decreases its volume If the volume stays the same, increasing the temperature increases the pressure If the pressure of the gas stays the same, increasing the temperature of the gas also increases the volume

Which two characteristics determine the state of matter? The arrangement and the motion of particles

Which state of matter has particles that are farthest apart? Gas

Which state of matter has particles that are generally close together? Solid

Which state of matter has particles that can slide past each other but cannot move freely in any direction liquid

What happens to the volume of a gas if the temperature stays the same and the pressure on the gas increases? It decreases

What happens to the pressure of a gas if the volume stays the same and the temperature increases? It increases

What happens to the volume of a gas if the pressure stays the same and the temperature increases? It increases

The End