Matter & Its Changes Holt – Chapter 1

Chemistry 1. A physical science that studies the composition, properties, and interaction of matter.

These Branches of Chemistry study … Organic – carbon compounds Inorganic – non-organic substances Physical – properties of matter, changes that occur in matter & relationships between matter & energy Analytical – identification of the composition of materials Biochemistry – living things Theoretical – properties of new compounds by the use of math and computers to design and predict

Chemical Investigations Basic research – gaining knowledge about a particular topic (i.e., reactions of an element) Applied research – solves a particular problem (i.e., finding chemicals that do not cause depletion of ozone in the atmosphere) Technical development – applying useful ideas to solve problems (usually occurs long after basic research)

Chemical Terms Mass – the measure of an amount of matter. Matter – anything that has mass and takes up space. Atom – smallest unit of matter that retains the properties of that matter. Compound – formed by chemical bonding of 2 or more atom types

Properties of Matter Physical – properties that can be measured without changing the identity of the substance (color, density, melting and freezing points) Chemical – relate to how a substance interacts with another substance to form a different substance Homogeneous Mixture – uniform composition (tea, solution) Heterogeneous Mixture – non-uniform composition (peanut butter) Pure substance – contains only 1 kind of substance (water)

More on Properties Extensive – depends on the amount of matter present (mass, amount) Intensive – properties of a substance (boiling point, freezing point, density)

Changes in Matter Physical – change of state or shape of a substance without the composition of the substance changing (ice melting) Chemical – involves the rearrangement of atoms of different elements in a substance and the formation of substances with different physical properties (baking a cake)

Energy and Chemistry Energy is either absorbed (ice melting) or released (liquid water freezing) in all chemical and physical changes. Energy is neither created nor destroyed; it changes form (chemical energy to light energy when fireworks explode)

The following graph shows the relationship between temperature and heat energy during the phase changes of water. Energy in Energy out

Phases of Matter Highest Energy to Lowest Plasma (many atoms have lost electrons) Gas Liquid Solid

Periodic Chart Basics The elements are in atomic number (# of protons) order. Horizontal rows are called periods Vertical columns are called families or groups

More on the Periodic Table Elements in the same groups or families share similar chemical properties. In a period, elements close together tend to have similar properties. Going across a period, physical and chemical properties change somewhat regularly across a period then repeat in the next period. A family of elements are in the same column. Elements in the same period are in the same horizontal row.

Metals Good conductors of heat and electricity Can be hammered or rolled into thin sheets (malleable) (some) are easy to cut with a knife Most are solids at room temperature Can be drawn into strands of wire (ductile) Have a shiny (metallic) luster Have high boiling points

Nonmetals Poor conductors of heat and electricity Brittle (break when pressure is applied) Have low boiling points

Noble Gases Aka: Inert gases Gaseous state at room temperature Generally don’t react with other elements

Matter Overview Matter is made up of either pure substances or mixtures. Pure substances can be compounds or elements which are both made up of atoms. Mixtures can be homogeneous (same throughout) or heterogeneous (different sized particles and substances)